# EDGAR Filing Document

**Accession Number:** 0001170858
**File Stem:** 0001292814-26-002897
**Filing Date:** 2026-5
**Character Count:** 263870
**Document Hash:** 0af2f7baf6b8b0d7ca5c5650b0cecc3a
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001292814-26-002897.hdr.sgml**: 20260508

**ACCESSION NUMBER**: 0001292814-26-002897

**CONFORMED SUBMISSION TYPE**: 6-K

**PUBLIC DOCUMENT COUNT**: 4

**CONFORMED PERIOD OF REPORT**: 20260331

**FILED AS OF DATE**: 20260508

**DATE AS OF CHANGE**: 20260508

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP
- **CENTRAL INDEX KEY:** 0001170858
- **STANDARD INDUSTRIAL CLASSIFICATION:** WATER SUPPLY [4941]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 000000000
- **STATE OF INCORPORATION:** D5
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 6-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-31317
- **FILM NUMBER:** 26956050

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** RUA COSTA CARVALHO, 300
- **STREET 2:** SAO PAULO
- **CITY:** SP
- **PROVINCE COUNTRY:** D5
- **BUSINESS PHONE:** 55-11-3388-8110

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** RUA COSTA CARVALHO, 300
- **STREET 2:** SAO PAULO
- **CITY:** SP
- **PROVINCE COUNTRY:** D5

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**SECURITIES AND EXCHANGE COMMISSION** 

**Washington, DC 20549** 

------

**FORM 6-K**

**REPORT OF FOREIGN ISSUER**<br>**PURSUANT TO RULE 13a-16 OR 15d-16 OF THE**

**SECURITIES EXCHANGE ACT OF 1934**

**For May, 2026** **(Commission File No. 1-31317)** 

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**Companhia de Saneamento Básico do Estado de São Paulo - SABESP** 

*(Exact name of registrant as specified in its charter)* 

**Basic Sanitation Company of the State of Sao Paulo - SABESP** 

*(Translation of Registrant's name into English)* 

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**Rua Costa Carvalho, 300 <br>São Paulo, S.P., 05429-900 <br>Federative Republic of Brazil** 

*(Address of Registrant's principal executive offices)* <br>

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Indicate by check mark whether the registrant files or will file <br>annual reports under cover Form 20-F or Form 40-F. <br>Form 20-F ___X___ Form 40-F ______

Indicate by check mark if the registrant is submitting the Form 6-K <br>in paper as permitted by Regulation S-T Rule 101(b)(1)__.

Indicate by check mark if the registrant is submitting the Form 6-K <br>in paper as permitted by Regulation S-T Rule 101(b)(7)__.

Indicate by check mark whether the registrant by furnishing the <br>information contained in this Form is also thereby furnishing the <br>information to the Commission pursuant to Rule 12g3-2(b) under <br>the Securities Exchange Act of 1934. <br>Yes ______ No ___X___

If "Yes" is marked, indicated below the file number assigned to the<br>registrant in connection with Rule 12g3-2(b):

**Companhia de Saneamento Básico do Estado de São Paulo – SABESP**

**Quarterly Financial Information for**

**the period ended March 31, 2026**

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Financial Position as of March 31, 2026 and December 31, 2025**<br> **In thousands of reais** | ![](image_001.jpg) |

---

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  |  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **Note** | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| **Current Assets** |  |  |  |  |  |
| Cash and cash equivalents | 7 | 3155200 | 4569998 | 3540240 | 4663226 |
| Financial investments | 8 | 15537279 | 7693630 | 15641914 | 7707745 |
| Trade receivables | 10 (a) | 4518755 | 4406829 | 4571688 | 4413449 |
| Accounts receivable from related parties | 11 (a) | 276021 | 276282 | 276096 | 276388 |
| Inventories |  | 125569 | 21863 | 125780 | 22061 |
| Restricted cash | 9 | 17864 | 9575 | 17864 | 9575 |
| Taxes Recoverable | 20 (a) | 1436108 | 1295237 | 1540437 | 1295310 |
| Assets held for sale |  | 48150 | 26864 | 48150 | 26864 |
| Other assets |  | 173748 | 159500 | 187137 | 141892 |
| **Total current assets** |  | **25288694** | **18459778** | **25949306** | **18556510** |
| **Non-current Assets** |  |  |  |  |  |
| Trade receivables | 10 (a) | 367159 | 258544 | 367159 | 258544 |
| Accounts receivable from related parties | 11 (a) | 852234 | 862782 | 852234 | 862782 |
| Escrow Deposits |  | 128989 | 120021 | 190446 | 120021 |
| Deferred income and social contribution taxes | 22 (a) |  |  | 41513 |  |
| Taxes Recoverable | 20 (a) |  |  | 267575 |  |
| Other assets |  | 32503 | 33509 | 32502 | 33509 |
| Investments | 12 | 1479309 | 494088 | 243146 | 254358 |
| Investment properties |  | 11478 | 49933 | 328066 | 49933 |
| Contract asset and other concession assets | 13 | 14255616 | 11006489 | 14268245 | 11018516 |
| Financial Asset of the Concession | 15 | 22125879 | 21665330 | 22321254 | 21665330 |
| Intangible assets | 14 | 50071845 | 50354751 | 50732495 | 50492473 |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Financial Position as of March 31, 2026 and December 31, 2025**<br> **In thousands of reais** | ![](image_001.jpg) |

---

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
| Property, plant, and equipment | 16 | 915655 | 890791 | 1124763 | 890791 |
| **Total non-current assets** |  | **90240667** | **85736238** | **90769398** | **85646257** |
| **Total Assets** |  | **115529361** | **104196016** | **116718704** | **104202767** |
|  |  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **Note** | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| **Current Liabilities** |  |  |  |  |  |
| Trade payables and contractors |  | 842069 | 2398445 | 872111 | 2400046 |
| Services payable | 27 | 2598708 | 2767899 | 2601742 | 2772416 |
| Borrowings and financing | 17 | 4884127 | 5132890 | 4872680 | 5092816 |
| Labor and social obligations | 25 | 407495 | 699629 | 435732 | 699629 |
| Taxes and contributions payable | 20 (b) | 292239 | 614078 | 303085 | 615592 |
| Deferred PIS/Cofins taxes | 21 | 81432 | 89049 | 81432 | 89049 |
| Dividends and interest on capital payable | 28 | 2059850 | 2059850 | 2063503 | 2059850 |
| Provisions | 23 (a) | 1380446 | 1370013 | 1380446 | 1370013 |
| Public-Private Partnership - PPP | 14 (c) | 473049 | 469687 | 473049 | 469687 |
| Derivative financial instruments | 19 | 1142171 | 521832 | 1484755 | 661421 |
| Performance Agreements | 14 (f) | 125766 | 120776 | 125766 | 120776 |
| Other liabilities |  | 218446 | 201620 | 228068 | 201619 |
| **Total current liabilities** |  | **14505798** | **16445768** | **14922369** | **16552914** |
| **Non-current Liabilities** |  |  |  |  |  |
| Borrowings and financing | 17 | 47114306 | 35168713 | 46769945 | 35049531 |
| Deferred income and social contribution taxes | 22 (a) | 3076274 | 3129908 | 3076274 | 3129908 |
| Deferred PIS/Cofins | 21 | 1218870 | 1191916 | 1218870 | 1191916 |
| Provisions | 23 (a) | 537877 | 533399 | 711943 | 533399 |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Financial Position as of March 31, 2026 and December 31, 2025**<br> **In thousands of reais** | ![](image_001.jpg) |

---

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
| Pension plan obligations | 26 | 2136163 | 2140161 | 2407944 | 2140161 |
| Public-Private Partnership - PPP | 14 (c) | 2851931 | 2856008 | 2851931 | 2856008 |
| Performance Agreements | 14 (f) | 3543 | 6151 | 3543 | 6151 |
| Contract liabilities | 24 |  |  | 626985 |  |
| Other liabilities |  | 383643 | 322868 | 304875 | 341655 |
| **Total non-current liabilities** |  | **57322607** | **45349124** | **57972310** | **45248729** |
| **Total liabilities** |  | **71828405** | **61794892** | **72894679** | **61801643** |
| Equity |  |  |  |  |  |
| Capital stock |  | 21379216 | 21210000 | 21379216 | 21210000 |
| Capital reserves |  | 65843 | 30219 | 65843 | 30219 |
| Earnings reserves |  | 21348996 | 21518212 | 21348996 | 21518212 |
| Treasury shares |  | (475385) | (475385) | (475385) | (475385) |
| Equity valuation adjustments |  | 117652 | 118078 | 117652 | 118078 |
| Retained earnings |  | 1264634 |  | 1264634 |  |
| **Total Equity - Controlling** |  | **43700956** | **42401124** | **43700956** | **42401124** |
| Non-Controlling Shareholders |  |  |  | 123069 |  |
| **Total equity** | 28 | **43700956** | **42401124** | **43824025** | **42401124** |
| **Total Liabilities and Equity** |  | **115529361** | **104196016** | **116718704** | **104202767** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Income for the**<br> **Periods ended March 31, 2026 and 2025**<br> **In thousands of reais, unless otherwise stated**  | ![](image_001.jpg) |

---

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  |  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **Note** | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| **Net operating revenue** | 31 | 9954560 | 8416021 | 9964842 | 8426200 |
| Operating costs | 32 | (6044720) | (4894875) | (6049315) | (4905642) |
| **Gross profit** |  | **3909840** | **3521146** | **3915527** | **3520558** |
| **Selling expenses** | 32 | (150560) | (172053) | (150846) | (172297) |
| Allowance for doubtful accounts | 10 (c) | (53493) | (136407) | (53602) | (136699) |
| Administrative expenses | 32 | (314963) | (399244) | (316898) | (397138) |
| Other operating income (expenses), net | 34 | (19800) | 18123 | (18827) | 18124 |
| Equity accounting | 12 | 12112 | 12567 | 8311 | 11348 |
| **Profit from operations before financial<br> income (expenses)** |  | **3383136** | **2844132** | **3383665** | **2843896** |
| Financial income, net | 33 | (1027004) | (594447) | (1026100) | (592970) |
| **Profit before income and social contribution taxes** |  | **2356132** | **2249685** | **2357565** | **2250926** |
| Income and social contribution taxes |  |  |  |  |  |
| Current | 22 (c) | (660735) | (694920) | (662168) | (696161) |
| Deferred | 22 (c) | 53634 | (72673) | 53634 | (72673) |
|  |  | (607101) | (767593) | (608534) | (768834) |
| **Profit for the period** |  | **1749031** | **1482092** | **1749031** | **1482092** |
| **Earnings per share - basic and diluted (in reais)** | 29 | 0.50 | 0.43 | 0.50 | 0.43 |

---

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Comprehensive Income for the**<br> **Periods ended March 31, 2026 and 2025**<br> **In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | |
|:---|:---|:---|:---|
|  |  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **Note** | **January to March 2026** | **January to March 2025** |
| **Profit for the period** |  | **1749031** | **1482092** |
| Items which will be subsequently reclassified to the income statement: |  | (426) | (12226) |
| &nbsp;&nbsp;&nbsp;&nbsp;Retained earnings (accumulated losses) on cash flow hedge, net of taxes | 19 |  | (12226) |
| &nbsp;&nbsp;&nbsp;&nbsp;Other adjustments |  | (426) |  |
| **Total comprehensive income for the period** |  | **1748605** | **1469866** |

---

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statement of Changes in Equity for the**<br> **Periods ended March 31, 2026 and 2025**<br> **In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  |  | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** | **Earnings reserves** |
|  | **Note** | **Capital stock** | **Treasury shares** | **Capital Reserve** <br>| **Legal reserve** | **Investment reserve** | **Retained Earnings/**<br> **Accumulated Losses** | **Equity valuation adjustments** | **Non- Controlling Shareholders** | **Total** |
| **Individual and Consolidated** |  | | | | | | | | | |
| **Balances as of December 31, 2024** |  | **15000000** | **-** | **-** | **2343583** | **19304132** | **—** | **280339** | **—** | **36928054** |
| Profit for the period |  |  |  |  |  |  | 1482092 |  |  | 1482092 |
| Gains and losses on financial instruments |  | - | - | - | - | - | - | (12226) | - | (12226) |
| **Total comprehensive income/(loss) for the period** |  | **-** | **-** | **-** | **-** | **-** | **1482092** | **(12226)** | **-** | **1482092** |
| Capital increase |  | 3400000 | - | - | - | (3400000) | - | - | - | - |
| **Balances as of March 31, 2026** |  | **18400000** | **-** | **-** | **2343853** | **15904132** | **1482092** | **268113** | **-** | **38397920** |
| **Balances as of December 31, 2025** |  | **21210000** | **(475385)** | **30219** | **2766686** | **18751526** | **—** | **118078** | **—** | **42401124** |
| Profit for the period |  |  |  |  |  |  | &nbsp;&nbsp;&nbsp;&nbsp;1749031 |  |  | &nbsp;&nbsp;&nbsp;&nbsp;1749031 |
| Other adjustments |  |  |  |  |  |  |  | (426) |  | (426) |
| **Total comprehensive income/(loss) for the period** |  | **—** | **—** | **—** | **—** | **—** | **1749031** | **(426)** | **—** | **1748605** |
| Capital increase | 28 (a) | 169216 |  |  |  | (169216) |  |  |  |  |
| Long-Term Incentive Plan | 28 (b) |  |  | 35624 |  |  |  |  |  | 35624 |
| Addition of non-controlling interest arising from business combination | 4 |  |  |  |  |  |  |  | 417090 | 417090 |
| Acquisition of non-controlling interest | 4 |  |  |  |  |  | (484397) |  | (294021) | (778418) |
| **Balances as of March 31, 2026** |  | **21379216** | **(475385)** | **65843** | **2766686** | **18582310** | **1264634** | **117652** | **123069** | **43824025** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Cash Flows for the**<br> **Periods ended March 31, 2026 and 2025**<br> **In thousands of reais, unless otherwise stated**  | ![](image_001.jpg) |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| **Cash flows from operating activities** |  |  |  |  |
| &nbsp;&nbsp;**Profit before income and social contribution taxes** | **2356132** | **2249685** | **2357565** | **2250926** |
| **Adjustments for reconciliation of net income:** |  |  |  |  |
| &nbsp;&nbsp;Depreciation and amortization | 696237 | 582326 | 697472 | 583560 |
| &nbsp;&nbsp;Residual value of property, plant and equipment, intangible assets and investment properties written-off | 1587 | 934 | 1587 | 934 |
| &nbsp;&nbsp;Allowance for doubtful accounts | 53493 | 136407 | 53602 | 136699 |
| &nbsp;&nbsp;Provisions and inflation adjustments on provisions | 29833 | 158411 | 29833 | 158411 |
| &nbsp;&nbsp;Interest calculated on borrowings and financing payable | 1292903 | 646698 | 1292903 | 646698 |
| &nbsp;&nbsp;Interest and inflation adjustments, net | (546103) | (159898) | (547396) | (160113) |
| &nbsp;&nbsp;Derivative financial instruments and mark-to-market | 228068 | 4570 | 228068 | 4570 |
| &nbsp;&nbsp;Financial Charges from Customers | (78220) | (87593) | (78222) | (87593) |
| &nbsp;&nbsp;Provision for Consent Decree (TAC), Knowledge Retention Program (KRP) and Incentivized Dismissal Program (IDP) and Voluntary Dismissal Program (VDP) | 69893 | (295866) | 69893 | (295866) |
| &nbsp;&nbsp; Equity Accounting | (12112) | (12567) | (8311) | (11348) |
| &nbsp;&nbsp;&nbsp;&nbsp;Interest and inflation adjustment (PPP) | 122675 | 159821 | 122675 | 159821 |
| &nbsp;&nbsp;&nbsp;&nbsp;Municipal transfers | 175359 | 120900 | 175452 | 120900 |
| &nbsp;&nbsp;Pension plan obligations | 41154 | 65272 | 41154 | 65272 |
| &nbsp;&nbsp;Deferred PIS and Cofins on financial asset of the concession | 31680 | 62885 | 31680 | 62885 |
| &nbsp;&nbsp;Financial asset of the concession - restatement | (342488) | (420229) | (342488) | (420229) |
| &nbsp;&nbsp;Other adjustments | 56089 | (12038) | 73023 | (9040) |
|  | **4176180** | **3199718** | **4198490** | **3206487** |
| Changes in assets |  |  |  |  |
| &nbsp;&nbsp;&nbsp;&nbsp;Trade receivables | (184274) | (148653) | (184664) | (152222) |
| &nbsp;&nbsp;Related-party balances and transactions | 35173 | 70291 | 35204 | 70287 |
| &nbsp;&nbsp;Inventories | (99009) | (50672) | (99022) | (50672) |
| &nbsp;&nbsp;Taxes Recoverable | (128326) | (21571) | (128743) | (21577) |
| &nbsp;&nbsp;Escrow Deposits | (8968) | 41907 | (8968) | 41907 |
| &nbsp;&nbsp;Other assets | (18474) | 35595 | 83783 | 33147 |
| &nbsp;&nbsp;Changes in liabilities |  |  |  |  |
| &nbsp;&nbsp;Trade payables and contractors | (97729) | (749490) | (58955) | (746743) |
| &nbsp;&nbsp;Services payable | (344550) | 423096 | (346126) | 422455 |
| &nbsp;&nbsp;Labor and social obligations | (370777) | (12261) | (370777) | (12261) |
| &nbsp;&nbsp;Taxes and contributions payable | (366900) | (305290) | (366970) | (304152) |
| &nbsp;&nbsp;Deferred PIS/Cofins | (12343) | (24012) | (12343) | (24012) |
| &nbsp;&nbsp;Provisions | (14922) | (55701) | (14922) | (55701) |
| &nbsp;&nbsp;Pension plan obligations | (62453) | (57008) | (62453) | (57008) |
| &nbsp;&nbsp;Other liabilities | 43578 | (119858) | (73955) | (119731) |
| &nbsp;&nbsp;**Cash generated from operations** | **2546206** | **2226091** | **2589579** | **2230204** |
| Interest Paid | (1268116) | (760885) | (1210954) | (760885) |

---

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Cash Flows for the**<br> **Periods ended March 31, 2026 and 2025**<br> **In thousands of reais, unless otherwise stated**  | ![](image_001.jpg) |

---

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| | | | | |
|:---|:---|:---|:---|:---|
| Income and social contribution taxes paid | (615674) | (366447) | (616987) | (368799) |
| **Net cash generated from operating activities** | **662416** | **1098759** | **761638** | **1100520** |
| **Cash flows from financing activities** |  |  |  |  |
| Acquisition of contract assets, intangible assets and property, plant and equipment | (5016963) | (1548895) | (5056694) | (1549922) |
| Restricted cash | (7996) | (1395) | (7996) | (1395) |
| Financial investments - Investment | (18889693) | (4352868) | (18982625) | (4360677) |
| Financial investments - Redemption | 11564384 | 4432087 | 11567987 | 4437855 |
| Dividends received | 8156 |  | 8156 |  |
| Acquisition of subsidiary, net of cash acquired (consolidated) | (682643) | - | (302293) | - |
| **Net cash used in investment activities** | **(13024755)** | **(1471071)** | **(12773465)** | **(1474139)** |
| **Cash flows from financing activities** |  |  |  |  |
| Borrowings and financing |  |  |  |  |
| &nbsp;&nbsp;Funding | 13873101 | 3636828 | 13873101 | 3636828 |
| &nbsp;&nbsp;&nbsp;&nbsp;Amortization | (1550259) | (1126479) | (1550259) | (1126479) |
| &nbsp;&nbsp;&nbsp;&nbsp;Acquisition of non-controlling interests | (739343) |  | (739343) |  |
| &nbsp;&nbsp;Public-Private Partnership - PPP | (123390) | (136484) | (123390) | (136484) |
| &nbsp;&nbsp;Derivative financial instruments - paid | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(512568) | (42699) | (571268) | (42699) |
| **Net cash generated from (used in) financing activities** | **10947541** | **2331166** | **10888841** | **2331166** |
| **Increase / (decrease) in cash and cash equivalents in the period** | **(1414798)** | **1958854** | **(1122986)** | **1957547** |
| **Represented by:** |  |  |  |  |
| Cash and cash equivalents at the beginning of the period | 4569998 | 1681204 | 4663226 | 1682606 |
| Cash and cash equivalents at the end of the period | 3155200 | 3640058 | 3540240 | 3640153 |
| **Increase / (decrease) in cash and cash equivalents in the period** | **(1414798)** | **1958854** | **(1122986)** | **1957547** |

---

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Statements of Value Added for the**<br> **Periods ended March 31, 2026 and 2025**<br> **In thousands of reais**  | ![](image_001.jpg) |

---

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  |  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **Note** | **March 31, 2026** | **March 31, 2025** | **March 31, 2026** | **March 31, 2025** |
| **Revenue** |  |  |  |  |  |
| Sanitation services (includes FAUSP) | 31 | 6739003 | 6329839 | 6406603 | 6339411 |
| Construction |  | 3632709 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2587970 | 3633311 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2588996 |
| Other revenue |  | 6558 | 23569 | 7531 | 23569 |
| Allowance for doubtful accounts | 10 (c) | (53493) | (136407) | (53602) | (136699) |
|  |  | **10324777** | **8804971** | **10336331** | **8815277** |
| **Inputs purchased from third parties** |  |  |  |  |  |
| Operating and construction costs |  | (4646824) | (3542731) | (4650069) | (3532660) |
| Materials, electricity, outsourced services, and others |  | (218263) | (365417) | (220309) | (366792) |
| Other operating expenses | 34 | (24855) | (4165) | (24852) | (4163) |
|  |  | **(4889942)** | **(3912313)** | **(4895230)** | **(3903615)** |
| **Gross value added** |  | **5434835** | **4892658** | **5441101** | **4911662** |
| **Retentions** |  |  |  |  |  |
| Depreciation and amortization | 32 | (696237) | (582326) | (697472) | (583560) |

| **Wealth received in transfer** |  |  |  |  |  |
| Equity Accounting | 12 | 12112 | 12567 | 8311 | 11348 |
| Financial income |  | 1217179 | 362550 | 1373599 | 364084 |
|  |  | **1229291** | **375117** | **1381910** | **375432** |
| **Total value added to distribute** |  | **5967889** | **4685449** | **6125539** | **4703534** |
| **Value added distribution** |  |  |  |  |  |
| **Personnel** |  |  |  |  |  |
| Direct Compensation |  | 418426 | 385655 | 418508 | 385940 |
| Benefits |  | 90245 | 166634 | 90272 | 166634 |
| Guarantee Fund for Length of Service (FGTS) |  | 37830 | 77596 | 37837 | 77596 |
|  |  | **546501** | **629885** | **546617** | **630170** |
| **Taxes, fees, and contributions** |  |  |  |  |  |
| Federal |  | 1136887 | 1382348 | 1138767 | 1385464 |
| State |  | 53702 | 49596 | 53825 | 49628 |
| Municipal |  | 25956 | 17492 | 25956 | 17492 |
|  |  | **1216545** | **1449436** | **1218548** | **1452584** |
| **Value distributed to providers of capital** |  |  |  |  |  |
| Interest, exchange rate changes and inflation adjustments |  | 2446479 | 1113502 | 2601995 | 1128153 |
| Rentals |  | 9333 | 10534 | 9348 | 10535 |
|  |  | **2455812** | **1124036** | **2611343** | **1138688** |
| **Value distributed to shareholders** |  |  |  |  |  |
| Retained earnings |  | 1749031 | 1482092 | 1749031 | 1482092 |
|  |  | 1749031 | 1482092 | 1749031 | 1482092 |
| **Value added distributed** |  | **5967889** | **4685449** | **6125539** | **4703534** |

---

![](image_002.jpg)

**May 7, 2026**

&nbsp;&nbsp;&nbsp;&nbsp;· 1Q26 adjusted EPS³ of R$0.44 versus
R$0.34 in 1Q25

&nbsp;&nbsp;&nbsp;&nbsp;· R$3.7 bn Capex in 1Q26 aimed at universal
access, +31% y/y

SÃO PAULO, SP – Sabesp (SBSP3) reported adjusted earnings of R$0.44 per share in the 1Q26, compared to R$0.34 per share in the same period of the previous year.

"We entered 2026 maintaining strong execution momentum. In 1Q26, investments totaled R$3.7 billion, a 31% increase versus 1Q25, supporting operational expansion and service quality improvements. Adjusted EBITDA reached R$3.8 billion (+26% y/y) and Adjusted Net Income¹ totaled R$1.6 billion (+32% y/y), reinforcing the consistency of our operating performance and financial discipline," said Daniel Szlak, CFO of Sabesp.

"Beyond the financial results, our priority continues to be delivering tangible advances in sanitation coverage and service standards. We are consistently outperforming the U-Factor benchmarks for the 2024–2026 cycle, with targets at 87% in water supply, 77% in sewage collection, and 71% in sewage treatment, reflecting sustained operational improvements rather than one-off gains.

Our investment program is driving broad social and economic impact by expanding access to essential services while strengthening communities through large-scale infrastructure execution, positioning the Company to sustain and scale these outcomes throughout 2026," said Carlos Piani, CEO of Sabesp.

**Consolidated Results**

For the quarter ended March 31, 2026, Sabesp reported adjusted earnings per share³ of R$0.44 compared to R$0.34 recorded in the same period of the previous year. Performance was driven by volume growth resulting from new connections (U-Factor targets fully attained), tariff gains and better collection, partially offset by the change in customer mix, with the expansion of consumers with access to subsidized rates².

The quarter sustained strong efficiency gains, driven by reductions in general and administrative expenses, headcount reduction, power optimization with shifts to the free market, and better collection rates. As a result, Adjusted EBITDA increased by 26%, reaching R$3.8 billion in 1Q26, while Adjusted Net Income grew by 32%, totaling R$1.6 billion

Sabesp invested R$3.7 bn in 1Q26, a 31% increase over the same period of the previous year, focusing on expansion projects directly aimed at meeting universalization targets.

**Earnings Conference Call**

Will be held on May 8, 2026, at 10:00 AM (Brasília time). Access link is available at the Company's Investor Relations website. The presentation has been made available at the same website. An audio recording of the call will be posted at the same <u>website</u>.

1. Excluding the update of the financial asset (indemnification)

2. Covered from July/25 onward by the amendment signed between
Sabesp and URAE-1
(<u>https://semil.sp.gov.br/urae1/wpcontent/uploads/sites/26/2025/08/2-Termo_Aditivo_Assinado_URAE1_ARSESP_SABESP.pdf)</u> 

3. Considers the stock split in the proportion 1:5 as approved
in the <u>EGM of April 28, 2026</u>![](image_002.jpg)

**REPORTED INCOME STATEMENT (CONSOLIDATED)**

**R$** **mn**

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** | &nbsp;&nbsp;**Var. (R$)** | &nbsp;&nbsp;**%** |
|  | &nbsp;&nbsp;Revenue from Operations | &nbsp;&nbsp;6366 | &nbsp;&nbsp;6120 | &nbsp;&nbsp;247 | &nbsp;&nbsp;4.0 |
|  | &nbsp;&nbsp;FAUSP | &nbsp;&nbsp;40 | &nbsp;&nbsp;(200) | &nbsp;&nbsp;240 | &nbsp;&nbsp;(120.0) |
|  | &nbsp;&nbsp;Financial Asset | &nbsp;&nbsp;342 | &nbsp;&nbsp;420 | &nbsp;&nbsp;(78) | &nbsp;&nbsp;(18.5) |
|  | &nbsp;&nbsp;Sales Tax | &nbsp;&nbsp;(418) | &nbsp;&nbsp;(502) | &nbsp;&nbsp;85 | &nbsp;&nbsp;(16.9) |
| **(=)** | &nbsp;&nbsp;**Net Sanitation Revenue** | &nbsp;&nbsp;**6332** | &nbsp;&nbsp;**5837** | &nbsp;&nbsp;**494** | &nbsp;&nbsp;**8.5** |
|  | &nbsp;&nbsp;Construction revenues | &nbsp;&nbsp;3633 | &nbsp;&nbsp;2589 | &nbsp;&nbsp;1044 | &nbsp;&nbsp;40.3 |
| **(=)** | &nbsp;&nbsp;**Net Revenue** | &nbsp;&nbsp;**9965** | &nbsp;&nbsp;**8426** | &nbsp;&nbsp;**1538** | &nbsp;&nbsp;**18.3** |
|  | &nbsp;&nbsp;Construction costs | &nbsp;&nbsp;(3633) | &nbsp;&nbsp;(2589) | &nbsp;&nbsp;(1044) | &nbsp;&nbsp;40.3 |
|  | &nbsp;&nbsp;Operating Costs and expenses | &nbsp;&nbsp;(2241) | &nbsp;&nbsp;(2439) | &nbsp;&nbsp;199 | &nbsp;&nbsp;(8.1) |
|  | &nbsp;&nbsp;Other operating income/(expense), net | &nbsp;&nbsp;(19) | &nbsp;&nbsp;18 | &nbsp;&nbsp;(37) | &nbsp;&nbsp;(203.9) |
|  | &nbsp;&nbsp;Minority Interest | &nbsp;&nbsp;8 | &nbsp;&nbsp;11 | &nbsp;&nbsp;(3) | &nbsp;&nbsp;(26.8) |
| **(=)** | &nbsp;&nbsp;**EBITDA** | &nbsp;&nbsp;**4080** | &nbsp;&nbsp;**3427** | &nbsp;&nbsp;**653** | &nbsp;&nbsp;**19.1** |
| *(%)* | &nbsp;&nbsp;*Margin* | &nbsp;&nbsp;*41%* | &nbsp;&nbsp;*41%* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*0.3* |
|  | &nbsp;&nbsp;Depreciation and Amortization | &nbsp;&nbsp;(697) | &nbsp;&nbsp;(584) | &nbsp;&nbsp;(114) | &nbsp;&nbsp;19.5 |
| **(=)** | &nbsp;&nbsp;**EBIT** | &nbsp;&nbsp;**3383** | &nbsp;&nbsp;**2844** | &nbsp;&nbsp;**539** | &nbsp;&nbsp;**19.0** |
|  | &nbsp;&nbsp;Net Financial result | &nbsp;&nbsp;(1025) | &nbsp;&nbsp;(593) | &nbsp;&nbsp;(432) | &nbsp;&nbsp;72.9 |
| **(=)** | &nbsp;&nbsp;**EBT** | &nbsp;&nbsp;**2358** | &nbsp;&nbsp;**2251** | &nbsp;&nbsp;**107** | &nbsp;&nbsp;**4.7** |
|  | &nbsp;&nbsp;Income tax | &nbsp;&nbsp;(609) | &nbsp;&nbsp;(769) | &nbsp;&nbsp;160 | &nbsp;&nbsp;(20.8) |
| **(=)** | &nbsp;&nbsp;**Net income** | &nbsp;&nbsp;**1749** | &nbsp;&nbsp;**1482** | &nbsp;&nbsp;**267** | &nbsp;&nbsp;**18.0** |
| *(%)* | &nbsp;&nbsp;*Margin* | &nbsp;&nbsp;*18%* | &nbsp;&nbsp;*18%* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*(0.0)* |
|  | &nbsp;&nbsp;EPS (R$) | &nbsp;&nbsp;0.50 | &nbsp;&nbsp;0.43 | &nbsp;&nbsp;- | &nbsp;&nbsp;- |

---

![](image_002.jpg)

**ADJUSTED INCOME STATEMENT (CONSOLIDATED)**

**1Q26**

**R$** **mn**

---

| | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**Adjustments** | &nbsp;&nbsp;**Adjustments** | &nbsp;&nbsp;**Adjustments** | &nbsp;&nbsp;**1Q26 Adjusted** | &nbsp;&nbsp;**1Q25 Adjusted** | &nbsp;&nbsp;**Var. (R$)** | &nbsp;&nbsp;**%** |
|  | | &nbsp;&nbsp;**1Q26** | | | | &nbsp;&nbsp;**1Q26 Adjusted** | &nbsp;&nbsp;**1Q25 Adjusted** | &nbsp;&nbsp;**Var. (R$)** | &nbsp;&nbsp;**%** |
|  | <br>&nbsp;&nbsp;Revenue from Operations | &nbsp;&nbsp;6366 | &nbsp;&nbsp;**Financial Asset**<br>&nbsp;&nbsp;- | &nbsp;&nbsp;**Construction**<br>&nbsp;&nbsp;- | &nbsp;&nbsp;**Non-Recurring**<br>&nbsp;&nbsp;- | &nbsp;&nbsp;6366 | &nbsp;&nbsp;6120 | &nbsp;&nbsp;247 | &nbsp;&nbsp;4.0 |
|  | &nbsp;&nbsp;FAUSP | &nbsp;&nbsp;40 | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;40 | &nbsp;&nbsp;(200) | &nbsp;&nbsp;240 | &nbsp;&nbsp;(120.0) |
|  | &nbsp;&nbsp;Financial Asset | &nbsp;&nbsp;342 | &nbsp;&nbsp;342 | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- |
|  | &nbsp;&nbsp;Sales Tax | &nbsp;&nbsp;(418) | &nbsp;&nbsp;(32) | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;(386) | &nbsp;&nbsp;(491) | &nbsp;&nbsp;105 | &nbsp;&nbsp;(21.5) |
| **(=)** | &nbsp;&nbsp;**Net Sanitation Revenue** | &nbsp;&nbsp;**6332** | &nbsp;&nbsp;**311** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**6021** | &nbsp;&nbsp;**5428** | &nbsp;&nbsp;**593** | &nbsp;&nbsp;**10.9** |
|  | &nbsp;&nbsp;Construction revenues | &nbsp;&nbsp;3633 | &nbsp;&nbsp;- | &nbsp;&nbsp;3633 | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- |
| **(=)** | &nbsp;&nbsp;**Net Revenue** | &nbsp;&nbsp;**9965** | &nbsp;&nbsp;**311** | &nbsp;&nbsp;**3633** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**6021** | &nbsp;&nbsp;**5428** | &nbsp;&nbsp;**593** | &nbsp;&nbsp;**10.9** |
|  | &nbsp;&nbsp;Construction costs | &nbsp;&nbsp;(3633) | &nbsp;&nbsp;- | &nbsp;&nbsp;(3633) | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- |
|  | &nbsp;&nbsp;Operating Costs and expenses | &nbsp;&nbsp;(2241) | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;(2241) | &nbsp;&nbsp;(2449) | &nbsp;&nbsp;209 | &nbsp;&nbsp;(8.5) |
|  | &nbsp;&nbsp;Other operating income/(expense), net | &nbsp;&nbsp;(19) | &nbsp;&nbsp;- | &nbsp;&nbsp;**-** | &nbsp;&nbsp;(16) | &nbsp;&nbsp;(3) | &nbsp;&nbsp;18 | &nbsp;&nbsp;(21) | &nbsp;&nbsp;(115.6) |
|  | &nbsp;&nbsp;Minority Interest | &nbsp;&nbsp;8 | &nbsp;&nbsp;- | &nbsp;&nbsp;**-** | &nbsp;&nbsp;- | &nbsp;&nbsp;8 | &nbsp;&nbsp;11 | &nbsp;&nbsp;(3) | &nbsp;&nbsp;(26.8) |
| **(=)** | &nbsp;&nbsp;**EBITDA** | &nbsp;&nbsp;**4080** | &nbsp;&nbsp;**311** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**(16)** | &nbsp;&nbsp;**3786** | &nbsp;&nbsp;**3008** | &nbsp;&nbsp;**778** | &nbsp;&nbsp;**25.9** |
| *(%)* | &nbsp;&nbsp;*Margin* | &nbsp;&nbsp;*41%* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;**-** | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*63%* | &nbsp;&nbsp;*55%* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*7.5* |
|  | &nbsp;&nbsp;Depreciation and Amortization | &nbsp;&nbsp;(697) | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;(697) | &nbsp;&nbsp;(584) | &nbsp;&nbsp;(114) | &nbsp;&nbsp;19.5 |
| **(=)** | &nbsp;&nbsp;**EBIT** | &nbsp;&nbsp;**3383** | &nbsp;&nbsp;**311** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**(16)** | &nbsp;&nbsp;**3088** | &nbsp;&nbsp;**2425** | &nbsp;&nbsp;**664** | &nbsp;&nbsp;**27.4** |
|  | &nbsp;&nbsp;Net Financial result | &nbsp;&nbsp;(1025) | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;- | &nbsp;&nbsp;(1025) | &nbsp;&nbsp;(638) | &nbsp;&nbsp;(387) | &nbsp;&nbsp;60.7 |
| **(=)** | &nbsp;&nbsp;**EBT** | &nbsp;&nbsp;**2358** | &nbsp;&nbsp;**311** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**(16)** | &nbsp;&nbsp;**2063** | &nbsp;&nbsp;**1787** | &nbsp;&nbsp;**276** | &nbsp;&nbsp;**15.5** |
|  | &nbsp;&nbsp;Income tax | &nbsp;&nbsp;(609) | &nbsp;&nbsp;(106) | &nbsp;&nbsp;(0) | &nbsp;&nbsp;5 | &nbsp;&nbsp;(508) | &nbsp;&nbsp;(611) | &nbsp;&nbsp;103 | &nbsp;&nbsp;(16.8) |
| **(=)** | &nbsp;&nbsp;**Net income** | &nbsp;&nbsp;**1749** | &nbsp;&nbsp;**205** | &nbsp;&nbsp;**-** | &nbsp;&nbsp;**(11)** | &nbsp;&nbsp;**1554** | &nbsp;&nbsp;**1176** | &nbsp;&nbsp;**379** | &nbsp;&nbsp;**32.2** |
| *(%)* | &nbsp;&nbsp;*Margin* | &nbsp;&nbsp;*18%* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;**-** | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*26%* | &nbsp;&nbsp;*22%* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*4.2* |
|  | &nbsp;&nbsp;EPS (R$)\* | &nbsp;&nbsp;0.50 | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*-* | &nbsp;&nbsp;0.44 | &nbsp;&nbsp;0.34 | &nbsp;&nbsp;*-* | &nbsp;&nbsp;*-* |

---

\*Balance adjusted by construction revenue/cost

Non-recurring effects on 1Q26 EBITDA: R$(16) mn related to M&A expenses.

Due to the migration to SAP S/4HANA, a temporary cutover reduced March 2026 billing by two days. This effect negatively impacted billing volumes and revenues in the period and is expected to be recovered over the subsequent months.

In 1Q26, total water production reached 778 million cubic meters, 4.6% lower year-over-year compared to 1Q25. This decline reflects a milder summer, with average temperatures 3.3 °C lower than last year, as well as the application of SP Aguas operational rule of the night pressure management implemented for approximately 10 hours per day to enhance the system resilience.

![](image_002.jpg)

**ADJUSTED NET REVENUE**

Adjusted net revenue from sanitation services, considering FAUSP and taxes, totaled R$6,021 mn in 1Q26, an increase of +10.9% vs 1Q25. The main factors that impacted revenue in the period were:

&nbsp;&nbsp;&nbsp;&nbsp;· +11.9% in net price: +9.1%
tariff phase-in and +2.8% due to commercial initiatives (large clients and revenue assurance);

&nbsp;&nbsp;&nbsp;&nbsp;· +2.4% in volume: New
units +2.9%, partially offset by lower average temperature (3.3)ºC and lower reservoir levels, affecting consumption per capita negatively;

&nbsp;&nbsp;&nbsp;&nbsp;· (3.4)% in mix: Growth
in units with access to subsidized rates;

**CONSUMPTION BY CATEGORY**

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | &nbsp;&nbsp;**Billed Volume (millions of m³)** | &nbsp;&nbsp;**Billed Volume (millions of m³)** | &nbsp;&nbsp;**Billed Volume (millions of m³)** | &nbsp;&nbsp;**Average Rate (R$/m³)** | &nbsp;&nbsp;**Average Rate (R$/m³)** | &nbsp;&nbsp;**Average Rate (R$/m³)** |
| &nbsp;&nbsp;**Category** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** | &nbsp;&nbsp;**%** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** | &nbsp;&nbsp;**%** |
| &nbsp;&nbsp;Residential | &nbsp;&nbsp;949 | &nbsp;&nbsp;939 | &nbsp;&nbsp;1.1 | &nbsp;&nbsp;4.31 | &nbsp;&nbsp;4.21 | &nbsp;&nbsp;2.3 |
| &nbsp;&nbsp;Commercial | &nbsp;&nbsp;95 | &nbsp;&nbsp;98 | &nbsp;&nbsp;(3.3) | &nbsp;&nbsp;15.46 | &nbsp;&nbsp;15.04 | &nbsp;&nbsp;2.8 |
| &nbsp;&nbsp;Industrial | &nbsp;&nbsp;17 | &nbsp;&nbsp;18 | &nbsp;&nbsp;(8.6) | &nbsp;&nbsp;20.82 | &nbsp;&nbsp;19.06 | &nbsp;&nbsp;9.2 |
| &nbsp;&nbsp;**Total Retail** | &nbsp;&nbsp;**1061** | &nbsp;&nbsp;**1055** | &nbsp;&nbsp;**0.5** | &nbsp;&nbsp;**5.57** | &nbsp;&nbsp;**5.47** | &nbsp;&nbsp;**1.7** |
| &nbsp;&nbsp;Wholesale | &nbsp;&nbsp;13 | &nbsp;&nbsp;13 | &nbsp;&nbsp;(3.0) | &nbsp;&nbsp;3.02 | &nbsp;&nbsp;2.76 | &nbsp;&nbsp;9.1 |
| &nbsp;&nbsp;Others¹ | &nbsp;&nbsp;23 | &nbsp;&nbsp;30 | &nbsp;&nbsp;(24.6) | &nbsp;&nbsp;21.62 | &nbsp;&nbsp;16.39 | &nbsp;&nbsp;31.9 |
| &nbsp;&nbsp;**Total** | &nbsp;&nbsp;**1096** | &nbsp;&nbsp;**1098** | &nbsp;&nbsp;**(0.2)** | &nbsp;&nbsp;**5.87** | &nbsp;&nbsp;**5.74** | &nbsp;&nbsp;**2.2** |

---

&nbsp;&nbsp;&nbsp;&nbsp;(1) Others are composed of Public, Own Building, and Mauá (BRK).

Wholesale and Others in 1Q25 was adjusted to incorporate the amount related to Olímpia.

---

| | | | | |
|:---|:---|:---|:---|:---|
| &nbsp;&nbsp;**Number of connections in thousands¹** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** | &nbsp;&nbsp;**Var.** | &nbsp;&nbsp;**%** |
| &nbsp;&nbsp;Water¹ | &nbsp;&nbsp;9468 | &nbsp;&nbsp;9491 | &nbsp;&nbsp;(22.5) | &nbsp;&nbsp;(0.2) |
| &nbsp;&nbsp;Sewage¹ | &nbsp;&nbsp;8211 | &nbsp;&nbsp;8219 | &nbsp;&nbsp;(7.8) | &nbsp;&nbsp;(0.1) |

---

(1) Active and registered connections, average at the end of the period

Not audited by external auditors

![](image_002.jpg)

**COST AND EXPENSE**

In 1Q26, OPEX decreased by 7.7% compared to 1Q25, representing a reduction of R$188 mn. This performance was mainly driven by: (i) R$170 mn in savings in personnel expenses, reflecting an 13% headcount reduction, workforce mix and labor benefits streamlining; (ii) energy cost savings, primarily due to the migration from the regulated market to the free market, reaching 86% (+12.6pp y/y). These effects were partially offset by higher general expenses related to municipal funds (FMSAI), reflecting higher revenues compared to last year.

**R$** **mn**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | &nbsp;&nbsp;**1Q26 Adjusted** | &nbsp;&nbsp;**1Q25 Adjusted** | &nbsp;&nbsp;**Var. (R$)** | &nbsp;&nbsp;**%** |
| &nbsp;&nbsp;Personnel | &nbsp;&nbsp;(485) | &nbsp;&nbsp;(655) | &nbsp;&nbsp;170 | &nbsp;&nbsp;(25.9) |
| &nbsp;&nbsp;General supplies | &nbsp;&nbsp;(122) | &nbsp;&nbsp;(70) | &nbsp;&nbsp;(53) | &nbsp;&nbsp;75.6 |
| &nbsp;&nbsp;Treatment supplies | &nbsp;&nbsp;(163) | &nbsp;&nbsp;(158) | &nbsp;&nbsp;(5) | &nbsp;&nbsp;2.9 |
| &nbsp;&nbsp;Services | &nbsp;&nbsp;(706) | &nbsp;&nbsp;(696) | &nbsp;&nbsp;(10) | &nbsp;&nbsp;1.4 |
| &nbsp;&nbsp;Power | &nbsp;&nbsp;(384) | &nbsp;&nbsp;(440) | &nbsp;&nbsp;56 | &nbsp;&nbsp;(12.7) |
| &nbsp;&nbsp;General expenses | &nbsp;&nbsp;(290) | &nbsp;&nbsp;(264) | &nbsp;&nbsp;(26) | &nbsp;&nbsp;9.8 |
| &nbsp;&nbsp;Tax expenses | &nbsp;&nbsp;(37) | &nbsp;&nbsp;(21) | &nbsp;&nbsp;(17) | &nbsp;&nbsp;81.5 |
| &nbsp;&nbsp;Allowance for doubtful accounts | &nbsp;&nbsp;(54) | &nbsp;&nbsp;(147) | &nbsp;&nbsp;93 | &nbsp;&nbsp;(63.5) |
| &nbsp;&nbsp;Other revenues and expenses¹ | &nbsp;&nbsp;(3) | &nbsp;&nbsp;18 | &nbsp;&nbsp;(21) | &nbsp;&nbsp;(115.6) |
| &nbsp;&nbsp;**Costs and Expenses** | &nbsp;&nbsp;**(2243)** | &nbsp;&nbsp;**(2431)** | &nbsp;&nbsp;**188** | &nbsp;&nbsp;**(7.7)** |
| &nbsp;&nbsp;Depreciation and Amortization | &nbsp;&nbsp;(697) | &nbsp;&nbsp;(584) | &nbsp;&nbsp;(114) | &nbsp;&nbsp;19.5 |
| &nbsp;&nbsp;**Costs, Expenses, Depreciation and Amortization** | &nbsp;&nbsp;**(2941)** | &nbsp;&nbsp;**(3015)** | &nbsp;&nbsp;**74** | &nbsp;&nbsp;**(2.4)** |

---

**PERSONNEL**

Sabesp ended 1Q26 with 8,927 employees, 8% reduction vs the same period of the previous year, and a 13% reduction

when considering the average number of employees.

---

| | | | | |
|:---|:---|:---|:---|:---|
| &nbsp;&nbsp;**Number of employees** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** | &nbsp;&nbsp;**Var. (Qty.)** | &nbsp;&nbsp;**%** |
| &nbsp;&nbsp;Employees at the end of each period | &nbsp;&nbsp;8927 | &nbsp;&nbsp;9700 | &nbsp;&nbsp;(773) | &nbsp;&nbsp;(8.0) |
| &nbsp;&nbsp;Employees - simple average | &nbsp;&nbsp;8814 | &nbsp;&nbsp;10089 | &nbsp;&nbsp;(1275) | &nbsp;&nbsp;(12.6) |

---

**CAPITAL EXPENDITURSES**

In 1Q26, CapEx totaled R$3,728 mn, an increase of 30.8% compared to the same period of the previous year.

**R$ mn**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** | &nbsp;&nbsp;**Var. (R$)** | &nbsp;&nbsp;**%** |
| &nbsp;&nbsp;Water | &nbsp;&nbsp;1243 | &nbsp;&nbsp;615 | &nbsp;&nbsp;627 | &nbsp;&nbsp;102.0 |
| &nbsp;&nbsp;Sewage | &nbsp;&nbsp;2485 | &nbsp;&nbsp;2236 | &nbsp;&nbsp;249 | &nbsp;&nbsp;11.2 |
| &nbsp;&nbsp;**Total** | &nbsp;&nbsp;**3728** | &nbsp;&nbsp;**2851** | &nbsp;&nbsp;**877** | &nbsp;&nbsp;**30.8** |

---

&nbsp;&nbsp;&nbsp;&nbsp;1. In 1Q25 minority interest was considered in Other Revenues and Expenses
line. This was changed in 2Q25. 1Q25 was adjusted to reflect the same criteria.

![](image_002.jpg)

**BALANCE SHEET (CONSOLIDATED)**

---

| | | |
|:---|:---|:---|
| &nbsp;&nbsp;**ASSETS** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**4Q25** |
| &nbsp;&nbsp;**Current assets** | | |
| &nbsp;&nbsp;Cash and Equivalents | &nbsp;&nbsp;3540240 | &nbsp;&nbsp;4663226 |
| &nbsp;&nbsp;ST investments | &nbsp;&nbsp;15641914 | &nbsp;&nbsp;7707745 |
| &nbsp;&nbsp;Trade receivables | &nbsp;&nbsp;4571688 | &nbsp;&nbsp;4413449 |
| &nbsp;&nbsp;Related parties | &nbsp;&nbsp;276096 | &nbsp;&nbsp;276388 |
| &nbsp;&nbsp;Inventories | &nbsp;&nbsp;125780 | &nbsp;&nbsp;22061 |
| &nbsp;&nbsp;Restricted cash | &nbsp;&nbsp;17864 | &nbsp;&nbsp;9575 |
| &nbsp;&nbsp;Taxes | &nbsp;&nbsp;1540437 | &nbsp;&nbsp;1295310 |
| &nbsp;&nbsp;Held for sale | &nbsp;&nbsp;48150 | &nbsp;&nbsp;26864 |
| &nbsp;&nbsp;Other assets | &nbsp;&nbsp;187137 | &nbsp;&nbsp;141892 |
| &nbsp;&nbsp;**Total Current assets** | &nbsp;&nbsp; **25949306** | &nbsp;&nbsp; **18556510** |
| &nbsp;&nbsp;**Fixed and LT assets** |  |  |
| &nbsp;&nbsp;Trade receivables | &nbsp;&nbsp;367159 | &nbsp;&nbsp;258544 |
| &nbsp;&nbsp;Related parties | &nbsp;&nbsp;852234 | &nbsp;&nbsp;862782 |
| &nbsp;&nbsp;Legal deposits | &nbsp;&nbsp;190446 | &nbsp;&nbsp;120021 |
| &nbsp;&nbsp;Deferred income tax and social contribution | &nbsp;&nbsp;41513 | &nbsp;&nbsp;- |
| &nbsp;&nbsp;Taxes to be recovered | &nbsp;&nbsp;267575 | &nbsp;&nbsp;- |
| &nbsp;&nbsp;Other assets | &nbsp;&nbsp;32502 | &nbsp;&nbsp;33509 |
| &nbsp;&nbsp;PP&E | &nbsp;&nbsp;243146 | &nbsp;&nbsp;254358 |
| &nbsp;&nbsp;Investments | &nbsp;&nbsp;328066 | &nbsp;&nbsp;49933 |
| &nbsp;&nbsp;Non-operating Property | &nbsp;&nbsp;14268245 | &nbsp;&nbsp;11018516 |
| &nbsp;&nbsp;Contract asset (Construction in progress) | &nbsp;&nbsp;22321254 | &nbsp;&nbsp;21665330 |
| &nbsp;&nbsp;Financial asset (Indemnity) | &nbsp;&nbsp;50732495 | &nbsp;&nbsp;50492473 |
| &nbsp;&nbsp;Intangible | &nbsp;&nbsp;1124763 | &nbsp;&nbsp;890791 |
| &nbsp;&nbsp;**Total noncurrent assets** | &nbsp;&nbsp; **90769398** | &nbsp;&nbsp; **85646257** |
| &nbsp;&nbsp;**Total Assets** | &nbsp;&nbsp; **116718704** | &nbsp;&nbsp; **104202767** |

---

---

| | | |
|:---|:---|:---|
| &nbsp;&nbsp;**LIABILITIES AND EQUITY** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**4Q25** |
| &nbsp;&nbsp;**Current liabilities** | | |
| &nbsp;&nbsp;Trade payables | &nbsp;&nbsp;872111 | &nbsp;&nbsp;2400046 |
| &nbsp;&nbsp;Services payable | &nbsp;&nbsp;2601742 | &nbsp;&nbsp;2772416 |
| &nbsp;&nbsp;ST Debt | &nbsp;&nbsp;4872680 | &nbsp;&nbsp;5092816 |
| &nbsp;&nbsp;Labor | &nbsp;&nbsp;435732 | &nbsp;&nbsp;699629 |
| &nbsp;&nbsp;Tax | &nbsp;&nbsp;303085 | &nbsp;&nbsp;615592 |
| &nbsp;&nbsp;Sales Tax | &nbsp;&nbsp;81432 | &nbsp;&nbsp;89049 |
| &nbsp;&nbsp;Dividends and IoC | &nbsp;&nbsp;2063503 | &nbsp;&nbsp;2059850 |
| &nbsp;&nbsp;Legal Accruals | &nbsp;&nbsp;1380446 | &nbsp;&nbsp;1370013 |
| &nbsp;&nbsp;Public-Private Partnership | &nbsp;&nbsp;473049 | &nbsp;&nbsp;469687 |
| &nbsp;&nbsp;Derivatives | &nbsp;&nbsp;1484755 | &nbsp;&nbsp;661421 |
| &nbsp;&nbsp;Performance Agreements | &nbsp;&nbsp;125766 | &nbsp;&nbsp;120776 |
| &nbsp;&nbsp;Others | &nbsp;&nbsp;228068 | &nbsp;&nbsp;201619 |
| &nbsp;&nbsp;**Total Current liabilities** | &nbsp;&nbsp; **14922369** | &nbsp;&nbsp; **16552914** |
| &nbsp;&nbsp;**Noncurrent Liabilities** |  |  |
| &nbsp;&nbsp;LT Debt | &nbsp;&nbsp;46769945 | &nbsp;&nbsp;35049531 |
| &nbsp;&nbsp;Tax | &nbsp;&nbsp;3076274 | &nbsp;&nbsp;3129908 |
| &nbsp;&nbsp;Salex Tax | &nbsp;&nbsp;1218870 | &nbsp;&nbsp;1191916 |
| &nbsp;&nbsp;Legal Accruals | &nbsp;&nbsp;711943 | &nbsp;&nbsp;533399 |
| &nbsp;&nbsp;Pension | &nbsp;&nbsp;2407944 | &nbsp;&nbsp;2140161 |
| &nbsp;&nbsp;Public-Private Partnership | &nbsp;&nbsp;2851931 | &nbsp;&nbsp;2856008 |
| &nbsp;&nbsp;Performance Contracts | &nbsp;&nbsp;3543 | &nbsp;&nbsp;6151 |
| &nbsp;&nbsp;Contract liabilities | &nbsp;&nbsp;626985 | &nbsp;&nbsp;- |
| &nbsp;&nbsp;Others | &nbsp;&nbsp;304875 | &nbsp;&nbsp;341655 |
| &nbsp;&nbsp;**Total Noncurrent Liabilities** | &nbsp;&nbsp; **57972310** | &nbsp;&nbsp; **45248729** |
| &nbsp;&nbsp;**Total Liabilities** | &nbsp;&nbsp; **72894679** | &nbsp;&nbsp; **61801643** |
| &nbsp;&nbsp;**Equity** |  |  |
| &nbsp;&nbsp;Capital stock | &nbsp;&nbsp;21379216 | &nbsp;&nbsp;21210000 |
| &nbsp;&nbsp;Capital reserves | &nbsp;&nbsp;65843 | &nbsp;&nbsp;30219 |
| &nbsp;&nbsp;Earnings reserves | &nbsp;&nbsp;21348996 | &nbsp;&nbsp;21518212 |
| &nbsp;&nbsp;Treasury Shares | &nbsp;&nbsp;(475385) | &nbsp;&nbsp;(475385) |
| &nbsp;&nbsp;Other Comprehensive Income | &nbsp;&nbsp;117652 | &nbsp;&nbsp;118078 |
| &nbsp;&nbsp;Retained Earnings/Accumulated Losses | &nbsp;&nbsp;1264634 | &nbsp;&nbsp;- |
| &nbsp;&nbsp;**Total Equity - Controlling Shareholders** | &nbsp;&nbsp; **43700956** | &nbsp;&nbsp; **42401124** |
| &nbsp;&nbsp;Interest of Non- Controlling Shareholders | &nbsp;&nbsp;123069 | &nbsp;&nbsp;- |
| &nbsp;&nbsp;**Total Equity** | &nbsp;&nbsp; **43824025** | &nbsp;&nbsp; **42401124** |
| &nbsp;&nbsp;**Total Equity and Liabilities** | &nbsp;&nbsp; **116718704** | &nbsp;&nbsp; **104202767** |

---

![](image_002.jpg)

**STATEMENT OF CASH FLOWS (CONSOLIDATED)**

---

| | | |
|:---|:---|:---|
| &nbsp;&nbsp;**R$ '000** | &nbsp;&nbsp;**1Q26** | &nbsp;&nbsp;**1Q25** |
| &nbsp;&nbsp;**Cash flows from operations** | &nbsp;&nbsp;**4198490** | &nbsp;&nbsp;**3206487** |
| &nbsp;&nbsp;Earnings before Tax | &nbsp;&nbsp;2357565 | &nbsp;&nbsp;2250926 |
| &nbsp;&nbsp; **Adjustments on net income:** |  |  |
| &nbsp;&nbsp;Depreciation and amortization | &nbsp;&nbsp;697472 | &nbsp;&nbsp;583560 |
| &nbsp;&nbsp;Fixed Assets write-off | &nbsp;&nbsp;1587 | &nbsp;&nbsp;934 |
| &nbsp;&nbsp;Allowance for doubtful accounts | &nbsp;&nbsp;53602 | &nbsp;&nbsp;136699 |
| &nbsp;&nbsp;Accruals and inflation over accruals | &nbsp;&nbsp;29833 | &nbsp;&nbsp;158411 |
| &nbsp;&nbsp;Interest owed | &nbsp;&nbsp;1292903 | &nbsp;&nbsp;646698 |
| &nbsp;&nbsp;Interest and inflation adjustments, net | &nbsp;&nbsp;(547396) | &nbsp;&nbsp;(160113) |
| &nbsp;&nbsp;Derivatives | &nbsp;&nbsp;228068 | &nbsp;&nbsp;4570 |
| &nbsp;&nbsp;Financial Charges from Customers | &nbsp;&nbsp;(78222) | &nbsp;&nbsp;(87593) |
| &nbsp;&nbsp;Voluntary dismissal plans | &nbsp;&nbsp;69893 | &nbsp;&nbsp;(295866) |
| &nbsp;&nbsp;Equity pick-up | &nbsp;&nbsp;(8311) | &nbsp;&nbsp;(11348) |
| &nbsp;&nbsp;PPP Interest and inflation | &nbsp;&nbsp;122675 | &nbsp;&nbsp;159821 |
| &nbsp;&nbsp;SP City Transfers | &nbsp;&nbsp;175452 | &nbsp;&nbsp;120900 |
| &nbsp;&nbsp;Pension | &nbsp;&nbsp;41154 | &nbsp;&nbsp;65272 |
| &nbsp;&nbsp;Deferred Sales Tax on financial assets (indemnity) | &nbsp;&nbsp;31680 | &nbsp;&nbsp;62885 |
| &nbsp;&nbsp;Update of financial asset (indemnity) | &nbsp;&nbsp;(342488) | &nbsp;&nbsp;(420229) |
| &nbsp;&nbsp;Others | &nbsp;&nbsp;73023 | &nbsp;&nbsp;(9040) |
|  | &nbsp;&nbsp;**4198490** | &nbsp;&nbsp;**3206487** |
| &nbsp;&nbsp;**Changes in assets** |  |  |
| &nbsp;&nbsp;Trade receivables | &nbsp;&nbsp;(184664) | &nbsp;&nbsp;(152222) |
| &nbsp;&nbsp;Related parties | &nbsp;&nbsp;35204 | &nbsp;&nbsp;70287 |
| &nbsp;&nbsp;Inventory | &nbsp;&nbsp;(99022) | &nbsp;&nbsp;(50672) |
| &nbsp;&nbsp;Tax | &nbsp;&nbsp;(128743) | &nbsp;&nbsp;(21577) |
| &nbsp;&nbsp;Escrow | &nbsp;&nbsp;(8968) | &nbsp;&nbsp;41907 |
| &nbsp;&nbsp;Others | &nbsp;&nbsp;83783 | &nbsp;&nbsp;33147 |
| &nbsp;&nbsp;**Changes in liabilities** |  |  |
| &nbsp;&nbsp;Trade payables | &nbsp;&nbsp;(58955) | &nbsp;&nbsp;(746743) |
| &nbsp;&nbsp;Services payables | &nbsp;&nbsp;(346126) | &nbsp;&nbsp;422455 |
| &nbsp;&nbsp;Labor | &nbsp;&nbsp;(370777) | &nbsp;&nbsp;(12261) |
| &nbsp;&nbsp;Income Tax | &nbsp;&nbsp;(366970) | &nbsp;&nbsp;(304152) |
| &nbsp;&nbsp;Sales Tax | &nbsp;&nbsp;(12343) | &nbsp;&nbsp;(24012) |
| &nbsp;&nbsp;Accruals | &nbsp;&nbsp;(14922) | &nbsp;&nbsp;(55701) |
| &nbsp;&nbsp;Pension | &nbsp;&nbsp;(62453) | &nbsp;&nbsp;(57008) |
| &nbsp;&nbsp;Others | &nbsp;&nbsp;(73955) | &nbsp;&nbsp;(119731) |
| &nbsp;&nbsp;**Cash from operations** | &nbsp;&nbsp;**2589579** | &nbsp;&nbsp;**2230204** |
| &nbsp;&nbsp;Interest paid | &nbsp;&nbsp;(1210954) | &nbsp;&nbsp;(760885) |
| &nbsp;&nbsp;Income tax | &nbsp;&nbsp;(616987) | &nbsp;&nbsp;(368799) |
| &nbsp;&nbsp;**Free cashflow from operations** | &nbsp;&nbsp;**761638** | &nbsp;&nbsp;**1100520** |

---

![](image_002.jpg)

---

| | | |
|:---|:---|:---|
| &nbsp;&nbsp;**Cash-flow from investments** | | |
| &nbsp;&nbsp;Contract, intangible assets and PP&E | &nbsp;&nbsp;(5056694) | &nbsp;&nbsp;(1549922) |
| &nbsp;&nbsp;Restricted Cash | &nbsp;&nbsp;(7996) | &nbsp;&nbsp;(1395) |
| &nbsp;&nbsp;Financial investments – Investment | &nbsp;&nbsp;(18982625) | &nbsp;&nbsp;(4360677) |
| &nbsp;&nbsp;Financial Investments – Withdrawal | &nbsp;&nbsp;11567987 | &nbsp;&nbsp;4437855 |
| &nbsp;&nbsp;Investment | &nbsp;&nbsp;8156 | &nbsp;&nbsp;- |
| &nbsp;&nbsp;Equity redemption/(injection) in subsidiaries | &nbsp;&nbsp;(302293) | &nbsp;&nbsp;- |
| &nbsp;&nbsp;**Free cashflow from investments** | &nbsp;&nbsp;**(12773465)** | &nbsp;&nbsp;**(1474139)** |
| &nbsp;&nbsp;**Cash flow from financing activity** |  |  |
| &nbsp;&nbsp;Borrowings |  |  |
| &nbsp;&nbsp; Debt issuance | &nbsp;&nbsp;13873101 | &nbsp;&nbsp;3636828 |
| &nbsp;&nbsp; Amortization | &nbsp;&nbsp;(1550259) | &nbsp;&nbsp;(1126479) |
| &nbsp;&nbsp;Acquisition of non-controlling interests | &nbsp;&nbsp;(739343) | &nbsp;&nbsp;- |
| &nbsp;&nbsp;PPP | &nbsp;&nbsp;(123390) | &nbsp;&nbsp;(136484) |
| &nbsp;&nbsp;Derivatives | &nbsp;&nbsp;(571268) | &nbsp;&nbsp;(42699) |
| &nbsp;&nbsp;**Free cashflow from financing activities** | &nbsp;&nbsp;**10888841** | &nbsp;&nbsp;**2331166** |
| &nbsp;&nbsp;**Increase / (decrease) in cash and cash equivalents in the period** | &nbsp;&nbsp;**(1122986)** | &nbsp;&nbsp;**1957547** |
| &nbsp;&nbsp;**Represented by:** |  |  |
| &nbsp;&nbsp;Cash and equivalents BoP | &nbsp;&nbsp;4663226 | &nbsp;&nbsp;1682606 |
| &nbsp;&nbsp;Cash and equivalents EoP | &nbsp;&nbsp;3540240 | &nbsp;&nbsp;3640153 |
| &nbsp;&nbsp;**Increase / (decrease) in cash and cash equivalents in the period** | &nbsp;&nbsp;**(1122986)** | &nbsp;&nbsp;**1957547** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

&nbsp;&nbsp;&nbsp;&nbsp;**1.** **Operations** 

Companhia de Saneamento Básico do Estado de São Paulo ("SABESP") is a publicly-held corporation headquartered in the municipality of São Paulo, at Rua Costa Carvalho, 300, CEP 05429-900. SABESP and its direct and indirect subsidiaries, individually or collectively (the "Company"), is engaged in the provision of basic and environmental sanitation services in São Paulo State, and supplies treated water and sewage services on a wholesale basis. SABESP may perform activities in other states and countries and can operate in drainage, urban cleaning, solid waste handling, and energy markets.

Since January 2026, following the acquisition of Empresa Metropolitana de Águas e Energia ("EMAE"), the Company has also begun operating in the planning, construction, operation, and maintenance of energy generation systems, as well as in the commercialization of electric power.

The Company's shares have been listed on the Novo Mercado segment of B3 under ticker SBSP3 since April 2002 and on the New York Stock Exchange ("NYSE") as Level III American Depositary Receipts ("ADRs"), under ticker SBS, since May 2002.

**Approvals**

The quarterly financial information was approved by the Board of Directors on May 7, 2026.

**2** **Basis of preparation and presentation of the quarterly information**

The quarterly information as of March 31 ,2026, was prepared based on the provisions of CPC 21 (R1) – Interim Financial Statements and the international standard IAS 34 – Interim Financial Reporting, issued by the International Accounting Standards Board (IASB), applicable to the preparation of Quarterly Information (ITR), and presented according to the rules issued by the CVM. Accordingly, this quarterly information takes into consideration the Circular Letter CVM/SNC/SEP 003 of April 28, 2011, which allows the entities to present selected notes to the financial statements in cases of redundant information already disclosed in the Annual Financial Statements. The quarterly information as of March 31, 2026, shall be read jointly with the Annual Financial Statements as of December 31, 2025, issued on March 16, 2026, prepared under the International Financial Reporting Standards (IFRS), issued by the International Accounting Standards Board (IASB), and the accounting practices adopted in Brazil, which observe the pronouncements issued by the Brazilian Accounting Pronouncements Committee (CPC). Therefore, the explanatory notes of this quarterly information are not presented or are not at the same level of detail and/or with the same reference as the notes included in the Annual Financial Statements (according to numerical references):

i. Summary of material accounting policy information (Note 3);

ii. Changes in accounting practices and disclosures (Note 4);

iii. Risk management - Financial instruments (Note 5.4);

iv. Significant accounting estimates and judgments (Note 6);

v. Balances and transactions with related parties (Note 11);

vi. Investments (Note 12);

vii. Intangible Assets (Note 15);

viii. Borrowings and financing (Note 17);

ix. Provisions (Note 23);

x. Pension plan obligations (Note 25);

xi. Equity (Note 27);

All material information related to the quarterly information, and this information alone, is being disclosed and corresponds to the information used by the Company's Management in its administration.

The Company prepared the financial statements on a going concern basis.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

The amounts disclosed in the Notes are presented in thousands of reais, unless otherwise stated.

**3** **Summary of material accounting policy information** 

The material accounting policy information used in the preparation of the quarterly information as of March 31, 2026, is consistent with that used to prepare the Annual Financial Statements for the year ended December 31, 2025. As a result of the business combination completed in the current quarter (Note 4), the following accounting policies have become applicable to the Company:

**Business combination**

Business combinations are accounted for using the acquisition method. The cost of an acquisition is measured by the sum of the consideration paid, which is evaluated based on the fair value on the acquisition date, and the value of any non-controlling interests in the acquiree. For each business combination, the acquirer must measure the non-controlling interest in the acquiree at fair value or based on its interest in the net assets identified in the acquiree. Costs directly attributable to the acquisition are accounted for as expense when incurred.

The Company determines that it has acquired a business when the acquired set of activities and assets includes, at least, an input of resources and a substantive process that together contribute significantly to the ability to generate output of resources. The process acquired is considered substantive if it is essential to the ability to develop or convert the input of resources acquired into outputs of resources (and the inputs of resources acquired include both the organized workforce with the skills, knowledge or experience necessary to perform this process); or is critical to the ability to continue producing outputs and is considered unique or scarce, or cannot be replaced without significant cost, effort or delay in the ability to continue producing outputs of resources.

Any contingent consideration to be paid by the acquirer will be recognized at fair value on the acquisition date. Subsequent changes in the fair value of the contingent consideration deemed as an asset or as a liability shall be recognized in accordance with CPC 48 / IFRS 9 in the profit or loss statement.

Initially, goodwill is measured as the excess of the consideration paid in relation to the net assets acquired (identifiable assets acquired, net, and liabilities assumed). If the consideration is less than the fair value of the net assets acquired, the difference shall be recognized as gain in the profit or loss statement.

After initial recognition, goodwill is measured at cost, less any accumulated impairment losses. For impairment testing purposes, the goodwill acquired in a business combination is, as of the acquisition date, allocated to each of the Company's cash-generating units that are expected to benefit from the synergies of the combination, regardless of whether other assets or liabilities of the acquiree are attributed to those units.

When a goodwill is part of a cash-generating unit and a portion of that unit is disposed of, the goodwill associated with the portion disposed of must be included in the cost of the operation when determining the gain or loss on disposal. The goodwill disposed of in these circumstances is calculated based on the proportional values of the portion disposed of in relation to the cash-generating unit held.

**4** **Business combination and acquisition of non-controlling interests** 

**Empresa Metropolitana de Águas e Energia S.A. ("EMAE")**

On January 21, 2026, the Company acquired 29.9% of the total capital and 74.9% of the voting capital of EMAE, representing 11,009,550 (eleven million, nine thousand, five hundred and fifty) common shares of the company that focuses on the planning, construction, operation and maintenance of electricity generation systems, as well as their commercialization, operating under a concession regime. The transaction was motivated by a combination of factors:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

&nbsp;&nbsp;&nbsp;&nbsp;• Advanced water integration ensuring security
of supply

&nbsp;&nbsp;&nbsp;&nbsp;• Operational synergy between water and energy

&nbsp;&nbsp;&nbsp;&nbsp;• Use of strategic window

&nbsp;&nbsp;&nbsp;&nbsp;• Technical and regulatory feasibility

This holistic approach reflects SABESP's strategy to strengthen its position as an essential services company in a context of climate challenges, growing demand and the need for better operational efficiency.

**Assets acquired and liabilities assumed**

In accordance with the provisions of CPC 15/IFRS 3, although the acquisition of control and, consequently, the business combination occurred on January 21, 2026, the Company considered the beginning of the acquisition month, i.e., January 1, 2026, for purposes of measuring the acquired assets and assumed liabilities, the Company adopted the beginning of the acquisition month, January 1, 2026, as the effective acquisition date, applying a three-month reporting lag as permitted by the applicable accounting standards. Based on this date, no results of the acquire are included in the consolidated financial statements. The fair value of EMAE's identifiable assets and liabilities as of that date is presented below:

---

| | | | |
|:---|:---|:---|:---|
|  | **Fair value recognized in the**<br> **acquisition** |  | **Fair value recognized in the**<br> **acquisition** |
| **Assets** |  | **Liabilities** |  |
| Cash and cash equivalents | 380350 | Trade payables and contractors | 28797 |
| Trade receivables | 46030 | Borrowings and financing | 448 |
| Taxes Recoverable | 371325 | Labor and social obligations | 28237 |
| Other assets | 136895 | Taxes and contributions payable | 9297 |
| Escrow Deposits | 61457 | Dividends and interest on capital payable | 10325 |
| Deferred income and social contribution taxes | &nbsp;&nbsp;&nbsp;&nbsp;41513 | Other liabilities | 29603 |
| Investment properties | 316589 | Borrowings and financing | &nbsp;&nbsp;&nbsp;&nbsp;3533 |
| Financial asset | 195375 | Provisions | 174066 |
| Intangible assets | 19253 | Pension plan obligations | 271781 |
| Property, plant, and equipment | 209108 | Contract liabilities | 626985 |
| **Total Assets** | **1777895** | **Total liabilities** | **1183072** |

---

---

| | |
|:---|:---|
| **Total net identifiable assets at fair value** | **594823** |
| Non-controlling interests measured at the proportionate share method | (417090) |
| Goodwill/Identifiable asset | 504910 |
| **Total consideration** | **682643** |

---

These effects are preliminary, as at the date of this disclosure the procedures for the purchase price allocation are still in progress, primarily related to the inspection of the acquired fixed assets, among other analyses. The final allocation of EMAE's purchase price depends on valuations and other studies that have not yet been completed, as well as on the issuance of the final appraisal report to be prepared by an independent specialized firm.

The goodwill/identifiable asset amounting to R$504,910 recognized upon the acquisition arises substantially from expected synergies associated with the business combination. This amount is provisional and subject to the completion of the

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

purchase price allocation (PPA) process, and may be adjusted as the fair value assessments of the identifiable assets acquired and liabilities assumed are finalized.

The Company adopted, as an accounting policy, the measurement and initial recognition of the non-controlling interest using the proportional interest share method.

The total consideration given was settled exclusively in cash, so that there are no clauses providing for supplementary payment by means of contingent payment, put/call option, issue or transfer of shares, assumption of liabilities or transfer of other assets to acquire the interest.

---

| | |
|:---|:---|
| **Analysis of the cash flow from acquisition** |  |
| Total consideration paid | (682643) |
| Net cash acquired from the subsidiary (included in cash flows from investment activities) | 380350 |
| **Net cash flow from acquisition** | **(302293)** |

---

The disclosure of pro forma net operating revenue and net income was not presented, as the acquisition balance sheet already reflects the effects as of the beginning of the fiscal year.

Transaction costs in the amount of R$16,000 were recognized in the profit or loss statement as general and administrative expenses.

**Acquisition of additional interest in EMAE**

After obtaining control, the Company acquired additional non-controlling interests, increasing its shareholding to 79.31%:

&nbsp;&nbsp;&nbsp;&nbsp;• On January 28, 2026, the Company acquired interest
representing 40.21% from Eletrobrás for the amount of R$567,705.

&nbsp;&nbsp;&nbsp;&nbsp;• On March 12, 2026, the Company acquired interest
representing 9.22% from Oceania for the amount of R$171,638.

The carrying amount of the net assets as of the acquisition date amounted to R$294,021. The breakdown of the additional interest acquired is shown below:

---

| | |
|:---|:---|
| Consideration paid to non-controlling shareholders | 739343 |
| Earn-out | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;39075 |
| Carrying value of the additional interest acquired | (295021) |
| Difference recognized in retained earnings | **484397** |

---

**5** **Risk management**

**5.1** **Financial risk management**

**Financial risk factors**

The Company's activities are affected by the Brazilian economic scenario, making it exposed to market risk (exchange rate and interest rate), credit risk, and liquidity risk. Financial risk management focuses on the unpredictability of financial markets and seeks to minimize potential adverse effects on financial performance. There were no changes in risk measurement policies, processes, and methods compared to the previous year.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(a)** **Market risk**

**Foreign currency risk**

It is the risk that the fair value of the future cash flows of a financial instrument will fluctuate due to variations in exchange rates. The Company's exposure to the risk of changes in exchange rates refers mainly to its financing activities, since the Company has foreign currency-denominated liabilities arising from long-term financing, in development institutions in US Dollar, Euro and Yen.

The management of currency exposure considers several current and projected economic factors, besides market conditions.

This risk arises from the possibility that the Company may incur losses due to exchange rate fluctuations that would impact liability balances of foreign currency-denominated borrowings and financing and related finance costs. The Company manages its foreign exchange risk through hedging transactions since 2024 and negotiates the terms of the derivatives in order to comply with the terms of the exposure hedged under Note 19.

Part of the total financial debt in the amount of R$17,879,630 as of March 31, 2026 (R$10,632,252 as of December 31, 2025), is indexed to the U.S. dollar, Euro and Yen. The exposure to currency risk is as follows:

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31,** <br> **2026** | **March 31,** <br> **2026** | **March 31,** <br> **2025** | **March 31,** <br> **2025** | **December 31,** <br> **2025** | **December 31,** <br> **2025** | **December 31, 2025** |  |
|  | **Foreign currency (in thousands)** | **R$** | **Foreign currency (in thousands)** | **R$** | **Foreign currency (in thousands)** | **R$** | **Foreign currency (in thousands)** | **R$** |
| Borrowings and financing – US$ | 2247849 | 11732423 | 2747849 | 14342123 | 750889 | 4131691 | 1250889 | 6882891 |
| Borrowings and financing – Yen | 60495723 | 1984865 | 60495723 | 1984865 | 62496777 | 2196137 | 62496777 | 2196137 |
| Borrowings and financing – EURO | 220000 | 1322574 | 220000 | 1322574 | 220000 | 1423224 | 220000 | 1423224 |
| Interest and charges from borrowings and financing – US$ |  | 143656 |  | 160878 |  | 44876 |  | 110009 |
| Interest and charges from borrowings and financing – Yen |  | 9020 |  | 9020 |  | 8818 |  | 8818 |
| Interest and charges from borrowings and financing – EURO |  | 24254 |  | 24254 |  | 12033 |  | 12033 |
| Fair value adjustment - US$ |  | 284023 |  | 267284 |  | 47666 |  | 143636 |
| Fair value adjustment - Yen |  | (99427) |  | (99427) |  | (67281) |  | (67281) |
| Fair value adjustment - EURO |  | 28329 |  | 28329 |  | 34631 |  | 34631 |
| **Total Exposure** |  | **15429717** |  | **18039900** |  | **7831795** |  | **10744098** |
| Borrowing cost – US$ |  | (170968) |  | (129303) |  | (61401) |  | (80063) |
| Borrowing cost – Yen |  | (12119) |  | (12119) |  | (12389) |  | (12389) |
| Borrowing costs – EURO |  | (18848) |  | (18848) |  | (19394) |  | (19394) |
| **Total foreign currency-denominated borrowings (Note 17)** |  | **15227782** |  | **17879630** |  | **7738611** |  | **10632252** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

The table below shows the prices and exchange rate changes in the period:

---

| | | | |
|:---|:---|:---|:---|
|  | **March 31, 2026** | **December 31, 2025** | **Variation** |
| US$ | R$5.2194 | R$5.5024 | -5.14% |
| EURO | R$6.0117 | R$6.4692 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- 7.07% |
| Yen | R$0.03281 | R$0.03514 | -6.63% |

---

As of March 31, 2026, if the Brazilian real had depreciated or appreciated by 10 percentage points, against the U.S. dollar, Yen and Euro with all other variables held constant, the effects on profit or loss before borrowing costs and taxes, for the three-month period ended March 31, 2026, would have been R$1,780,976 (R$305,835 for the three-month period ended March 31, 2025), upwards or downwards, excluding the effects of to the hedging instruments (Note 19).

The Company understands that it could comfortably accommodate any devaluation scenario due to derivative financial instruments such as cross-currency swaps already contracted.

**Interest rate risk**

It is the risk that the fair value of the future cash flows of a financial instrument will fluctuate due to variations in market interest rates. For most transactions, the Company manages the interest rate risk by entering into derivative financial instruments that effectively swap their exposures for liabilities indexed to the CDI.

The table below shows the borrowings and financing subject to different inflation adjustment indices, including the derivative instrument:

---

| | | | | |
|:---|:---|:---|:---|:---|
| **Individual** | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| &nbsp;&nbsp;CDI (i) | 45977065 | 33593125 | 43142285 | 30722218 |
| &nbsp;&nbsp;TR (ii) | 1604468 | 1629756 | 1604468 | 1629756 |
| &nbsp;&nbsp;IPCA (iii) | 2972898 | 2924904 | 5582598 | 5582893 |
| &nbsp;&nbsp;TJLP (iv) | 765263 | 825206 | 765263 | 825206 |
| &nbsp;&nbsp;Interest and charges | 1025860 | 1204818 | 1013965 | 1164744 |
| &nbsp;&nbsp;**Total** | **52345554** | **40177809** | **52108579** | **39924817** |

---

(i) CDI - (Certificado de Depósito Interbancário), an interbank deposit certificate

(ii) TR - Benchmark Interest Rate

(iii) IPCA - (Índice Nacional de Preços ao Consumidor Amplo), a consumer price index

(iv) TJLP - (Taxa de Juros a Longo Prazo), a long-term interest rate index

Another risk to which the Company is exposed is the mismatch of inflation adjustment indices of its debts with those of its service revenues and financial assets, adjusted by the IPCA. Tariff adjustments of services provided do not necessarily follow the increases in the adjustments indices of borrowings, financing, and interest rates affecting indebtedness.

As of March 31, 2026, if interest rates on borrowings and financing had been 1 percentage point higher or lower with all other variables held constant, the effects on consolidated profit before taxes for the three-month period ended March 31,

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

2026, would have been R$521,086 (R$260,714 as of March 31, 2025), upwards or downwards, mainly as a result of lower or higher interest expenses on floating rate borrowings and financing.

The table below shows the sensitivity analysis of the financial instruments, prepared under CPC 40 (R1)/ IFRS 7, to evidence the balances of main financial assets and liabilities, calculated at a rate projected for the twelve-month period after March 31, 2026, or until the final settlement of each contract, whichever occurs first, considering a probable scenario.

The purpose of the sensitivity analysis is to measure the impact of changes in the market on the financial instruments, considering all other variables constant. At the time of settlement, the amounts may be different from those presented, due to the estimates used in the measurement.

The table below considers the impact of the derivative instrument:

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** |
| **Indicators** | **Exposure** | **Probable scenario** | **Exposure** | **Probable scenario** |
| Assets |  |  |  |  |
| CDI | 18679922 | 13.85% | 18679922 | 13.85% |
| Financial income |  | 2587169 |  | 2587169 |
| Liabilities |  |  |  |  |
| CDI | (45977065) | 13.85% | (43142285) | 13.85% |
| Interest to be incurred |  | (6367824) |  | (5975206) |
| **Net exposure – CDI** | **(27297143)** | **(3780654)** | **(24462363)** | **(3388037)** |
| Assets |  |  |  |  |
| IPCA | 22125879 | 4.00% | 22125879 | 4.00% |
| Financial asset of the concession |  | 884039 |  | 884039 |
| Liabilities |  |  |  |  |
| IPCA | (2972898) | 4.00% | (5582598) | 4.00% |
| Interest to be incurred |  | (118782) |  | (138760) |
| **Net exposure – IPCA** | **19152981** | **765257** | **16543281** | **745280** |
| Liabilities |  |  |  |  |
| TR | (1604468) | 2.02% | (1604468) | 2.02% |
| Expenses to be incurred |  | (32410) |  | (32410) |
| TJLP | (765263) | 9.27% | (765263) | 9.27% |
| Interest to be incurred |  | (70958) |  | (70958) |
| **Total net expenses to be incurred** |  | **(3118766)** |  | **(2746126)** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(b)** **Credit risk**

Credit risk is related to cash and cash equivalents, financial investments, as well as credit exposures of customers, including accounts receivable, restricted cash, accounts receivable from related parties, and financial asset of the concession. Credit risk exposure to customers is mitigated by sales to a dispersed base, without risk of concentration, while credit risk exposure to cash and investment is mitigated by the Financial Investment Guideline followed by the Company.

The maximum exposure to credit risk as of March 31, 2026, is the carrying amount of instruments classified as cash and cash equivalents, financial investments, restricted cash, trade receivables, accounts receivable from related parties, and financial asset of the concession at the reporting date. See Notes 7, 8, 9, 10, 11, and 15.

Regarding the financial assets held with financial institutions, the credit quality was assessed by reference to external credit ratings (if available) or historical information about the bank's default rates. For the credit quality of the banks, such as deposits and financial investments, the Company assesses the rating published by three main international agencies (Fitch, Moody's and S&P).

As of March 31, 2026, all investments were made with financial institutions whose rating disclosed by Fitch or Moody's was AAA (bra) or AAA.br.

**(c)** **Liquidity risk** 

Liquidity is primarily reliant upon cash provided by operating activities and borrowings and financing obtained in the local and international capital markets, as well as the payment of debts. The management of this risk considers the assessment of its liquidity requirements to ensure it has sufficient cash to meet its operating and capital expenditure requirements.

The funds held are invested in interest-bearing current accounts, time deposits, and securities, with instruments with appropriate maturity or liquidity to provide margin as determined by the projections mentioned above.

The table below shows the financial liabilities, by maturity, including the installments of principal and future interest. For agreements with floating interest rates, the interest rates used correspond to the base date of March 31, 2026.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **2027** | **2028** | **2029** | **2030** | **2031** | **2032 to 2049** | **Total** |
| **As of March 31, 2026** |  |  |  |  |  |  |  |
| Liabilities |  |  |  |  |  |  |  |
| Borrowings and financing | 4501267 | 2193706 | 1444652 | 3684405 | 7062707 | &nbsp;&nbsp;&nbsp;&nbsp;33111696 | 51998433 |
| Interest on borrowings and financing | 3001422 | 4403293 | 4255760 | 4023578 | 3737555 | 11147599 | 30569207 |
| Trade payables and contractors | 842069 | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | 842069 |
| Services payable | 2598708 | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | 2598708 |
| Public-Private Partnership - PPP | 199222 | 239066 | 239066 | 239066 | 239066 | 2169494 | 3324980 |
| Interest Public-Private Partnership - PPP | 192280 | 247101 | 264235 | 281850 | 300082 | 3125341 | 4410889 |
| **Total** | **11334968** | **7083166** | **6203713** | **8228899** | **11339410** | **49554130** | **93744286** |
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **2027** | **2028** | **2029** | **2030** | **2031** | **2032 to 2049** | **Total** |
| **As of March 31, 2026** |  |  |  |  |  |  |  |
| Liabilities |  |  |  |  |  |  |  |
| Borrowings and financing | 4490184 | 2194758 | 1445580 | 3685222 | 6715184 | &nbsp;&nbsp;&nbsp;&nbsp;33111697 | 51642625 |
| Interest on borrowings and financing | 2949948 | 4300533 | 4151343 | 3920819 | 3634797 | 11147599 | 30105039 |
| Trade payables and contractors | 872111 | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | 872111 |
| Services payable | 2601742 | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | 2601742 |
| Public-Private Partnership - PPP | 199222 | 239066 | 239066 | 239066 | 239066 | 2169494 | 3324980 |
| Interest Public-Private Partnership - PPP | 192280 | 247101 | 264235 | 281850 | 300082 | 3125341 | 4410889 |
| **Total** | **11305487** | **6981458** | **6100224** | **8126957** | **10889129** | **49554131** | **92957386** |

---

*Cross default*

The Company has borrowings and financing agreements including cross-default clauses, i.e., the early maturity of any debt may imply the early maturity of these agreements. The indicators are continuously monitored to avoid the execution of these clauses, and the most restrictive ratios are shown in Note 17 (c).

**(d)** **Derivative financial instruments**

Under the Financial Risk Management Policy and the Derivatives Transactions Program, which aim to manage financial risks and mitigate exposure to market variables that impact assets, liabilities, and/or cash flows, the Company enters into hedging instruments, especially for its foreign-currency financing, reducing the effects of undesirable fluctuations from these variables on its transactions.

Criteria and guidelines for financial risk management were established to mitigate imbalances between assets and liabilities that have some sort of indexation exclusively to hedge the Company's indexed assets and liabilities that present some mismatch, without characterizing financial leverage.

The Company uses risk ratings disclosed by Standard Poor's (S&P), Moody's, or Fitch to support and complement the analysis and judgment of banking risk.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**5.2 Capital Management**

The Company's objectives in managing capital are to ensure the Company's ability to continue increasing investments in infrastructure, provide returns for shareholders and benefits for other stakeholders, and maintain an optimal capital structure to reduce the cost of capital.

Capital is monitored based on the financial leverage ratio, which corresponds to net debt divided by total capital (shareholders and providers of capital). Net debt corresponds to total borrowings and financing less cash and cash equivalents and financial investments. Total capital is calculated as total equity plus net debt, as shown in the statement of financial position.

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31,**<br> **2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Total borrowings and financing (Note 17) | 51998433 | 40301603 | &nbsp;&nbsp;&nbsp;&nbsp;51642625 | 40142347 |
| (-) Cash and cash equivalents (Note 7) | (3155200) | (4569998) | (3540240) | (4663226) |
| (-) Financial investments (Note 8) | (15537279) | (7693630) | (15641914) | (7707745) |
| Net debt | 33305954 | 28037975 | 32460471 | 27771376 |
| Total Equity | 43700956 | 42401124 | &nbsp;&nbsp;&nbsp;&nbsp;43824025 | 42401124 |
| Total capital (shareholders plus providers of capital) | 77006910 | 70439099 | 76284496 | 70172500 |
| Leverage ratio | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;43% | 40% | 42% | 40% |

---

**6** **Significant accounting estimates and judgments**

The preparation of the quarterly information requires Management to disclose judgments (except for those that involve estimates) that have a significant impact on the amounts recognized based on experience and other factors deemed as relevant, which affect the amounts of assets and liabilities and present results that may differ from the actual results.

The Company establishes estimates and assumptions concerning the future, which are reviewed on a timely basis. Such accounting estimates, by definition, may differ from the actual results. The effects arising from the reviews of the accounting estimates are recognized in the period in which the estimates are reviewed.

The Company assessed the main accounting policies that involve judgments, except for those that involve estimates, and concluded that none of them have a significant effect.

The areas that require a higher level of judgment and greater complexity are disclosed below. The assumptions and estimates for each of these areas, when applicable, are presented in the related notes:

---

| | |
|:---|:---|
| **Area** | **Reference** |
| Unbilled revenue | Note 10 |
| Allowance for doubtful accounts | Note 10 (c) |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | |
|:---|:---|
| Contract assets, intangible assets, and financial assets arising from concession contracts | Notes 13, 14 and 15 |
| Assessment of the recoverable amount of non-financial assets (impairment) | Note 14 |
| Derivative financial instruments | Note 19 |
| Deferred income and social contribution taxes | Note 22 |
| Provisions | Note 23 |
| Pension obligations – Pension plans | Note 26 |

---

**7** **Cash and cash equivalents**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Cash and banks | 32758 | 2185 | 37448 | 95411 |
| Cash equivalents | 3122442 | 4567813 | 3502792 | 4567815 |
| **Total** | **3155200** | **4569998** | **3540240** | **4663226** |

---

Cash and cash equivalents include cash, bank deposits, and high-liquidity short-term financial investments, mainly represented by daily liquidity CDBs (divided between Banco Itaú, Banco Santander, Banco Bradesco, and Banco do Brasil), whose original maturities or intention of realization are equal to or less than three months, which are convertible into a cash amount and subject to an insignificant risk of change in value.

Of the total balance presented in this item as of March 31, 2026, approximately 99.75% refers to the amounts recorded in Banco Itaú, Banco Santander, Banco Bradesco, and Banco do Brasil.

As of March 31, 2026, the average yield of cash equivalents corresponded to 99.80% of the CDI (99.66% as of December 31, 2025).

**8** **Financial investments**

&nbsp;&nbsp;&nbsp;&nbsp;**(a)** **Current** 

The Company has financial investments in CDB, with daily liquidity, which it does not intend to use in the next three months, as shown below:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Banco BV | 174 | 169 | 174 | 169 |
| Banco Bradesco | 5803577 | 1118026 | 5803577 | 1118026 |
| Banco Santander S/A | 3792816 | 3699510 | 3792816 | 3699510 |
| Banco BTG Pactual S/A | 2192391 | 2132826 | 21923912 | 2132826 |
| Banco Itaú | 3000818 |  | 3087092 |  |
| Banco do Brasil S/A | 86732 | 83594 | 105093 | 97709 |
| Brazilian Federal Savings Bank | 31068 | 30206 | 31068 | 30206 |
| XP Investimentos | 226599 | 215002 | 226599 | 215002 |
| Banco Citibank | 403104 | 414297 | 403104 | 414297 |
| **Total** | **15537279** | **7693630** | **15641914** | **7707745** |

---

As of March 31, 2026, the average yield of the financial investments corresponded to 99.8% of the CDI (99,6% as of December 31, 2025).

**9** **Restricted cash**

Restricted cash balances refer to amounts held by the Company as a result of contractual obligations and specific agreements. As of March 31, 2026, and December 31, 2025, restricted cash operations were R$17,864 and R$9,575, respectively.

The amounts recorded in 2024 were mainly related to the agreements signed with the São Paulo Municipal Government ("PMSP) and with URAE-1, which provided for the deduction of a portion of the revenue destined to the Municipal Fund for Environmental Sanitation and Infrastructure ("FMSAI) to cover any defaults by public agencies.

These amounts were redeemed throughout 2025, especially between October and November, resulting in the elimination of the balances linked to the agreements with the PMSP.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**10** **Trade receivables** 

**(a) Statement of financial position details**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Private sector: |  |  |  |  |
| General (i) and special customers (ii) | 2536629 | 2431979 | 2587973 | 2436976 |
| Agreements (iii) | 327030 | 343747 | 327030 | 343747 |
|  | 2863659 | 2775726 | 2915003 | 2780723 |
| Governmental Entities: |  |  |  |  |
| Municipal | 1147549 | 1186815 | 1147218 | 1186531 |
| Federal | 2765 | 2670 | 2765 | 2670 |
| Agreements (iii) | 333396 | 274508 | 333396 | 274508 |
|  | 1483710 | 1463993 | 1483379 | 1463709 |
| Wholesale customers – Municipal<br> governments: (iv) |  |  |  |  |
| Mogi das Cruzes | 13898 | 9149 | 13898 | 9149 |
| São Caetano do Sul | 34204 | 26884 | 34204 | 26884 |
| São Caetano do Sul - Agreement | 49173 | 51589 | 49173 | 51589 |
| Total wholesale customers – Municipal<br> governments | 97275 | 87622 | 97275 | 87622 |
| Unbilled supply (v) | 1194014 | 1155475 | 1195934 | 1157382 |
| Sub-total | 5638658 | 5482816 | 5691591 | 5489436 |
| Allowance for doubtful accounts | (752744) | (817443) | (752744) | (817443) |
| **Total** | **4885914** | **4665373** | **4938847** | **4671993** |
| Current | 4518755 | 4406829 | 4571688 | 4413449 |
| Non-current | 367159 | 258544 | 367159 | 258544 |
| **Total** | **4885914** | **4665373** | **4938847** | **4671993** |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) General customers - residential, and small and mid-sized companies;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) Special customers – large consumers, industrial and commercial customers, condominiums and special
billing customers (fixed demand agreements, industrial waste, wells, among others);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) Agreements - installment payments of past-due receivables, plus inflation adjustment and interest, according
to the agreements;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iv) Wholesale basis customers - municipal governments. This balance refers to the sale of treated water to
municipalities, which are responsible for distributing to, billing, and charging end consumers.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(v) Unbilled Supplies: represents revenue incurred, for which the service has been provided but has not yet
billed by the end of each period, and is recognized as trade receivables based on monthly estimates.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(b) The aging of trade receivables is as follows:**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| **Current** | **3070915** | **2960281** | **3120497** | **2963070** |
| Past-due: |  |  |  |  |
| Up to 30 days | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;804672 | 747338 | 806380 | 748559 |
| From 31 to 60 days | 328971 | 308672 | 329556 | 309579 |
| From 61 to 90 days | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;208256 | 228767 | 208602 | 229559 |
| From 91 to 120 days | 215827 | 242688 | 216053 | 243256 |
| From 121 to 180 days | 304777 | 276103 | 305319 | 276446 |
| From 181 to 360 days | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;209459 | 226600 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;209463 | 226600 |
| Over 360 days | 495781 | 492367 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;495721 | 492367 |
| **Total Past Due** | **2567743** | **2522535** | **2571094** | **2526366** |
| **Total** | **5638658** | **5482816** | **5691591** | **5489436** |

---

**(c) Allowance for doubtful accounts ("ADA")**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
| **Changes in assets** | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| **Balance at the beginning of year** | **817443** | **1248209** | **817443** | **1248209** |
| Recognition/(reversal) of allowance | (27270) | (30750) | (27270) | (30750) |
| Recoveries | (37429) | (34466) | (37429) | (34466) |
| **Balance at the end of year** | **752744** | **1182993** | **752744** | **1182993** |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
| **Reconciliation of estimated / historical losses in profit or loss - accounts receivable and related parties** | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| Write-offs | &nbsp;&nbsp;&nbsp;&nbsp;(117348) | &nbsp;&nbsp;&nbsp;&nbsp;(201244) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(117457) | (201536) |
| (Losses)/reversal with state entities - related parties | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(844) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(379) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(844) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(379) |
| (Losses)/reversal with the private sector/government entities | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;27270 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;30750 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;27270 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;30750 |
| Recoveries | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;37429 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;34466 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;37429 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;34466 |
| **Amount recorded as expense (Note 32)** | **(53493)** | **(136407)** | **(53602)** | **(136699)** |

---

The Company does not have customers individually accounting for 10% or more of its total revenues.

**(d) Registered warrants**

The Company has registered warrants issued as a result of final and unappealable lawsuits for the collection of unpaid water and sewage bills from public entities in the amount of R$823,238 thousand (R$814,290 thousand as of December 31, 2025). These bills are covered in full by ADA, and the restated amounts of said bills, calculated according to the respective registered warrants, are not recognized due to uncertainties about their realization.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

Accordingly, the reversal of the ADA for the original bills and their restatement are recognized when uncertainties about their realization are mitigated, i.e. when the realizable value is determinable due to the predictability of the commencement of their receipt, without uncertainties or discussions about these amounts or when negotiated with third parties.

Additionally, the Company negotiated registered warrants for overdue bills with the municipalities of Guarulhos, Santo André, and Mauá in previous fiscal years, which are currently suspended as they serve as collateral for the provision of services in these municipalities.

As of March 31, 2026, the Company holds registered warrants recognized in the amount of R$823,238 (R$814,290 as of December 31, 2025). This amount forms part of the Company's total trade and other receivables balance of R$5,638,658 thousand as of March 31, 2026.

**11** **Related-party balances and transactions**

**(a)** **São Paulo State**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(i)** **Accounts receivable, interest on equity, revenue, expenses and financial receipts** 

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31,** <br> **2026** | **December 31, 2025** | **March 31,** <br> **2026** | **December 31, 2025** |
| **Current** |  |  |  |  |
| Accounts receivable: |  |  |  |  |
| Sanitation services | 172513 | 163759 | 172588 | 163865 |
| Allowance for losses | (43597) | (42753) | (43597) | (42753) |
| Reimbursement of additional retirement and pension benefits paid (G0): |  |  |  |  |
| Monthly flow | 19251 | 32141 | 19251 | 32141 |
| GESP Agreement – 2015 | 127854 | 123135 | 127854 | 123135 |
| **Total current** | **276021** | **276282** | **276096** | **276388** |
| **Non-current** |  |  |  |  |
| Agreement for the installment payment of sanitation services | 1361 | 1361 | 1361 | 1361 |
| Reimbursement of additional retirement and pension benefits paid (G0): |  |  |  |  |
| GESP Agreement – 2015 | 850873 | 861421 | 850873 | 861421 |
| **Total non-current** | **852234** | **862782** | **852234** | **862782** |
| **Total receivable** | **1128255** | **1139064** | **1128330** | **1139170** |
| **Assets:** |  |  |  |  |
| Sanitation services | 130277 | 122367 | 130352 | 122473 |
| Reimbursement of additional retirement and pension benefits paid (G0) | 997978 | 1016697 | 997978 | 1016697 |
| **Total** | **1128255** | **1139064** | **1128330** | **1139170** |
| **Liabilities:** |  |  |  |  |
| Dividends and interest on capital payable | 428681 | 428681 | 428681 | 428681 |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| Revenue from sanitation services | 226234 | 221207 | 226275 | 221240 |
| Payments received from related parties | (207625) | (208372) | (207625) | (208372) |
| Reimbursement received referring to Law No. 4.819/1958<br>| (60512) | (116628) | (60512) | (116628) |

---

The information below refers to the Individual and Consolidated balances and transactions.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(ii)** **Disputed amounts** 

As of March 31, 2026, and December 31, 2025, the disputed amounts between SABESP and the São Paulo State, referring to additional retirement and pension benefits paid (Law No. 4,819/1958), totaled R$1,843,857 and R$1,808,631, respectively, and an ADA was recognized for the total amount.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(iii)** **Actuarial Liability** 

The Company recognized an actuarial liability corresponding to additional retirement and pension benefits paid to employees, retired employees, and pensioners of the G0 (Note 26). As of March 31, 2026, and December 31, 2025, the amounts corresponding to such actuarial liability were R$2,043,866 and R$2,140,161, respectively. Of the total paid, the São Paulo State reimburses approximately 50%. For detailed information on additional retirement and pension benefits, see Note 26.

**(iv) Agreements with reduced tariffs for Federal, State and Municipal Entities that join the Rational Water Use Program (PURA)** 

The Company maintains joinder agreements to the PURE Program with public entities operating in the São Paulo State. The purpose of the program is to promote the conscious use of water, granting participating entities a 25% tariff discount, provided that they are in a regular situation of compliance and meet the established goals.

**(v) Guarantees** 

The São Paulo State provides guarantees for some of the Company's borrowings and financing and does not charge any related fees, see Note 17.

**(vi) FEHIDRO**

The Company formalized three financing agreements under the State Fund for Water Resources (FEHIDRO). The funds are aimed at the execution of works and sewage services. As of March 31, 2026, the balance of these financings was R$1,210, recorded under the "Other" line in borrowings and financing (R$938 as of December 31, 2025).

**(vii) Privatization**

According to Article 7 of Law 9,361/1996, the controlling shareholder will be reimbursed, upon the privatization, the services of independent audit firms, law firms, opinions, or specialized studies necessary for the privatization.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

The amount to be reimbursed by the São Paulo State as of March 31, 2026 and December 31, 2025 was R$85,929, recorded under "Other assets".

**(b)** **Non-operating assets**

As of March 31, 2026 and December 31, 2025, the Company had an amount of R$3,521 related to land and lent structures under free lease agreements.

**(c)** **SABESPREV** 

The Company sponsors a defined benefit plan (G1 Plan), which is operated and administered by SABESPREV. The net actuarial commitment recognized until March 31, 2026 was R$92,296 (R$99,514 as of December 31, 2025). See Note 26.

**(d)** **Key Management Personnel Compensation**

The expenses related to the compensation of key management personnel were R$28,741 and R$8,975 for the years 2025 and 2024, respectively. In addition, the total compensation of the management corresponds to R$45,623, which include short-term benefits to management personnel.

---

| | | |
|:---|:---|:---|
| **Compensation** | **March 31, 2026** | **December 31, 2025** |
| Short-term benefits to employees and key management personnel | 20267 | 39828 |
| Share-based payments (\*) | - | 22618 |
| **Total compensation** | **20267** | **62446** |

---

(\*) Refers to shares granted during the period. See Note 28 (b).

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(e)** **Águas de Andradina** 

As of March 31, 2026, the balance of principal and interest of the loan agreement entered into between the parties was R$4,925, recorded under "Other assets" in current assets (R$4,718 in current assets as of December 31, 2025), at DI + 3% p.a.

This loan agreement was executed on August 17, 2021 and will be settled with the purchase and sale transaction.

**(f)** **Equatorial S.A.**

In July 2024, Equatorial Participações e Investimentos IV S.A., controlled by Equatorial S.A., acquired shares representing 15% (fifteen percent) of the share capital of SABESP. In December 2024, Equatorial S.A. absorbed its subsidiary, becoming the direct holder of the equity interest in SABESP. As of March 31, 2026, the balance of dividends and interest on equity payable was R$348,402.

**(g)** **SABESP Luxembourg ("SABESP Lux")**

On August 1, 2025, the Company issued the 36th issue of simple non-convertible unsecured debentures, in the total amount of 2,815,700, with a unit par value of R$1, with maturity in 2030 and a yield of IPCA + 9.28% p.a. Of these debentures, 2,765,700 were acquired by SABESP Luxembourg (98.22% of the total securities of this issue). This transaction involved entering into a derivative instrument swapping the yield for CDI (see Note 19).

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(i) Use of Reservoirs ("EMAE")**

Empresa Metropolitana de Águas e Energia S/A - EMAE intended to receive credit and financial compensation for alleged past and future losses of electricity generation due to water abstraction and compensation for costs already incurred and to be incurred with the operation, maintenance and inspection of Guarapiranga and Billings reservoirs that SABESP uses in its operations.

On October 28, 2016, a Private Instrument of Transaction and Other Covenants were executed with the purpose of definitively settling the disputes, while maintaining SABESP's authorization to use the aforementioned reservoirs.

As of March 31, 2026, the outstanding balance of the agreement amounted to R$10,036 and R$109,292 (December 31, 2025: R$9,745 and R$105,884), recognized under "Other obligations" in the Company's current and non-current liabilities, respectively.

As a result of the acquisition of EMAE's control, consummated on January 26, 2026 (see note 4), the balances and obligations arising from this agreement, as transactions between companies that are part of the same economic group, are fully eliminated in the consolidated financial statements.

**12** **Investments**

The following are events in the year that are related to investees:

**SABESP Participações S.A.**

On January 30, 2026, SABESP Participações S.A., a wholly-owned subsidiary of the Company, approved a capital increase of R$15,648, through the issue of 15,648,701 common shares, subscribed and paid in by the Company.

The payment was made through the verification of the equity interests previously held directly by the Company in the affiliates Águas de Andradina S.A. and Águas de Castilho S.A., corresponding to 30% of the capital of each company, valued at book value, based on a report prepared by an independent appraiser, pursuant to Law No. 6,404/76. Of the total, R$12,201 refer to the interest in Águas de Andradina S.A. and R$3,447 to the interest in Águas de Castilho S.A.

As a result of this transaction, SABESP began to indirectly hold such investments through SABESP Participações. This is an intra-group corporate reorganization, which did not result in an effect on the Company's shareholders' equity, cash or consolidated results.

**EMAE**

With the acquisition of EMAE's control, as well as the additional acquisition of shares held by non-controlling shareholders in January 2026, the Company became the holder of 79.31% of said company. For further details, see Note 4.

The Company holds equity interest valued under the equity method in the following investees:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Equity** | **Equity** | **Additions** | **Write-offs** | **Dividends** | **Comprehensive Income** <br>| **Profit (loss) for the Period** | | | **Equity Interest Percentage** | **Equity Interest Percentage** |
|  | **March 31, 2026** | **December 31, 2025** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **(\*)** | **January to March 2025** | **March 31, 2026** | **December 31, 2025** |
| Sesamm | 95110 | 91455 |  |  |  |  | 3655 |  | 4722 | 36% | 36% |
| Águas de Andradina |  | 41291 |  | (41291) |  |  |  |  | 1397 | — % | 30% |
| Águas de Castilho |  | 12060 |  | (12060) |  |  |  |  | 603 | — % | 30% |
| Attend Ambiental | 60841 | 60961 |  |  | (6450) |  | 6330 |  | 9309 | 45% | 45% |
| Aquapolo Ambiental | 151984 | 143988 |  |  |  |  | 7996 |  | 10485 | 49% | 49% |
| Paulista Geradora de Energia | 23544 | 22769 |  |  |  |  | 775 |  | 174 | 25% | 25% |
| Cantareira SP Energia | 11046 | 10975 |  |  |  |  | 70 | 1 | 8 | 49% | 49% |
| Barueri Energia Renovável | 250623 | 252212 |  |  |  |  | (1589) |  | (1620) | 20% | 20% |
| SABESP Luxembourg | 7162 | 8452 |  |  |  | (426) | (864) |  |  | 100% | 100% |
| SABESP Participações | 103012 | 85001 | 15649 | (15649) |  |  | 2362 |  |  | 100% | 100% |
| SABESP Olímpia | 165648 | 162671 |  |  |  |  | 2977 |  | 1219 | 100% | 100% |
| EMAE (\*\*\*) | 594823 |  | 594823 |  |  |  |  |  |  | 79% |  |
| Concessionária Sabesp URAE-1 | 1 | 1 |  |  |  |  |  |  |  | 100% | 100% |

---

(\*) The amount presented refers to the changes in the investee's equity, since its financial statements for the year ended December 31, 2025 were issued after the disclosure of SABESP's financial statements.

(\*\*) Refers to amounts as of January 1, 2026. See Note 4 for further details.

The balances of investments and the respective changes are as follows:

---

| | | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **Investments** | **Investments** | **Additions** | **Write-off** | **Dividends** | **Comprehensive Income** | **Reclassification (\*\*)** | **Equity Accounting** | **Equity Accounting** | **Equity Accounting** |
|  | **March 31, 2026** | **December 31, 2025** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **January to March 2026** | **(\*)** | **January to March 2025** |
| Sesamm | 34240 | 32924 |  |  |  |  |  | 1316 |  | 1700 |
| Águas de Andradina |  | 12387 |  | (12201) |  |  |  | (186) |  | 418 |
| Águas de Castilho |  | 3618 |  | (3447) |  |  |  | (171) |  | 181 |
| Attend Ambiental | 27379 | 27433 |  |  | (2903) |  |  | 2849 |  | 4189 |
| Aquapolo Ambiental | 74473 | 70555 |  |  |  |  |  | 3918 |  | 5138 |
| Paulista Geradora de Energia | 5886 | 5693 |  |  |  |  |  | 193 |  | 45 |
| Cantareira SP Energia | 5412 | 5378 |  |  |  |  |  | 34 |  | 9 |
| Barueri Energia Renovável | 50126 | 50443 |  |  |  |  |  | (317) |  | (324) |
| Infranext |  |  |  |  |  |  |  |  |  |  |
| SABESP Luxembourg | 7162 | 8452 |  |  |  | (426) |  | (864) |  |  |
| SABESP Participações | 103012 | 85001 | 15649 |  |  |  |  | 2362 |  |  |
| SABESP Olímpia | 165648 | 162670 |  |  |  |  |  | 2978 |  | 1219 |
| EMAE | 471754 |  | 471754 |  |  |  |  |  |  |  |
| **Total** | **945092** | **464554** | **487403** | **(15648)** | **(2903)** | **(426)** | **—** | **12112** |  | **12575** |
| **Others investments** | **534217** | **29534** |  |  |  |  |  |  |  |  |
| **Total** | **1479309** | **494088** |  |  |  |  |  |  |  |  |

---

(\*) The amount presented refers to changes in the equity of the investee, as its financial statements for the year ended December 31, 2025 were issued after the disclosure of SABESP's financial statements.

(\*\*) The amount of the investee's loss in excess of the investment was reclassified to Non-current Liabilities.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **Investments** | **Investments** | **Dividends** | **Equity Accounting** | **Equity Accounting** | **Equity Accounting** |
|  | **March 31, 2026** | **December 31, 2025** | **January to March 2026** | **January to March 2026** | **(\*)** | **January to March 2025** |
| Sesamm | 34240 | 32924 |  | 1316 |  | 1700 |
| Águas de Andradina | 12569 | 12387 |  | 182 |  | 418 |
| Águas de Castilho | 3754 | 3618 |  | 136 |  | 181 |
| Attend Ambiental | 27379 | 27433 | (2903) | 2849 |  | 4189 |
| Aquapolo Ambiental | 74473 | 70555 |  | 3918 |  | 5138 |
| Paulista Geradora de Energia | 5886 | 5693 |  | 193 |  | 45 |
| Cantareira SP Energia | 5412 | 5378 |  | 34 |  | 9 |
| Barueri Energia Renovável | 50126 | 50443 |  | (317) |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(324) |
| **Total** | **213839** | **208431** | **(2903)** | **8311** | **—** | **11356** |
| Other investments | 29307 | 45927 |  |  |  |  |
| **Total** | **243146** | **254358** |  |  |  |  |

---

(\*) The amount presented refers to changes in the equity of the investee, as its financial statements for the year ended December 31, 2025 were issued after the disclosure of SABESP's financial statements.

**13** **Contract assets and other concession assets**

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025** | **Additions (i)** | **Write-offs** | **Transfers** | **Transfers to intangible assets (ii)** | **Transfer to the concession's financial assets** | **March 31, 2026 (iii)** |
| Contract Assets and other concession assets | 11006489 | 3755847 |  |  | (388658) | (118062) | 14255616 |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025** | **Additions (i)** | **Write-offs** | **Transfers** | **Transfers to intangible assets (ii)** | **Transfer to the concession's financial assets** | **March 31, 2026 (iii)** |
| Contract Assets and other concession assets | 11018516 | 3756449 |  |  | (388658) | (118062) | 14268245 |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2024** | **Additions** | **Write-offs** | **Transfers** | **Transfers to intangible assets** | **Transfer to the concession's financial assets** | **March 31, 2025** |
| Contract Assets and other concession assets | 4872410 | 2788002 |  | 3 | (589908) | (168104) | 6902403 |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2024** | **Additions** | **Write-offs** | **Transfers** | **Transfers to intangible assets** | **Transfer to the concession's financial assets** | **December 31, 2025** |
| Contract Assets and other concession assets | 4877667 | 2789029 |  | 3 | (589908) | (168104) | 6908687 |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) The largest additions in the period were located
in the municipalities of São Paulo, Guarulhos, and Praia Grande, in the amounts of R$1,490 million, R$346 million and R$141
million, respectively. Furthermore, the Company recognizes in the additions other concession assets:

---

| | | |
|:---|:---|:---|
| **Other concession assets (changes)** | **Individual** | **Consolidated** |
| Other additions (iv) | 123138 | 123138 |
| Construction Revenue (Note 31) | 3632709 | 3633311 |
| **Total additions** | **3755847** | **3756449** |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) The largest transfers in the period were located
in the municipalities of São Paulo, Guarulhos, and Franca, totaling R$190 million, R$29 million, and R$22 million, respectively.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) The largest works are located in the municipalities
of São Paulo, Guarulhos and Praia Grande, totaling R$4,514 million, R$1,081 million, and R$446 million, respectively.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iv) Refers to other additions that did not have
construction revenue as a corresponding offset, consisting mainly of advances and inventories related to construction projects, software,
and provisions for unrecorded invoices.

As of March 31, 2026, and December 31, 2025, the contract asset and other concession assets had no amounts recognized as right-of-use leases.

&nbsp;&nbsp;&nbsp;&nbsp;**(a)** **Capitalization of interest and other finance charges** 

The Company capitalizes interest, inflation adjustments, and exchange rate changes in contract assets and other concession assets during the construction period. From January to March 2026, the Company capitalized R$233,801 (R$173,738 from January to March 2025).

**(b)** **Expropriations** 

As a result of the construction of priority projects related to water and sewage systems, the Company is required to expropriate third-party properties, whose owners are compensated either amicably or in court. The costs of such expropriations are recorded in the contract asset and other concession assets during the execution of the works. From January to March 2026, the total amount referring to expropriations was R$10,938 (from January to March 2025 – R$14,446).

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**14** **Intangible assets**

**(a)** **Statement of financial position details**

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Cost** | **Amortization** | **Net** | **Cost** | **Amortization** | **Net** |
| Intangible assets arising from: |  |  |  |  |  |  |
| Concession agreements - others | 135321 | (61060) | 74261 | 135470 | (60381) | 75089 |
| Contract Commitments (i) | 4437857 | (740756) | 3697101 | 4437857 | (707736) | 3730121 |
| Concession Agreements - URAE-1 | 69665817 | (23905142) | 45760675 | 69281545 | (23335074) | 45946471 |
| Software license of use | 1696773 | (1191411) | 505362 | 1696773 | (1145671) | 551102 |
| Right of use – other assets | 240646 | (206200) | 34446 | 240646 | (188678) | 51968 |
| **Total** | **76176414** | **(26104569)** | **50071845** | **75792291** | **(25437540)** | **50354751** |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Cost** | **Amortization** | **Goodwill** | **Net** | **Cost** | **Accumulated Amortization** | **Net** |
| Intangible assets arising from: |  |  |  |  |  |  |  |
| Concession agreements - new contracts | 148000 | (11511) |  | 136489 | 148000 | (10275) | 137725 |
| Concession agreements - others | 135321 | (61060) |  | 74261 | 135470 | (60381) | 75089 |
| Contract Commitments (i) | 4437857 | (740756) |  | 3697101 | 4437857 | (707736) | 3730121 |
| Concession Agreements - URAE-1 | 69665817 | (23905142) |  | 45760675 | 69281545 | (23335074) | 45946471 |
| Software license of use | 1728294 | &nbsp;&nbsp;&nbsp;&nbsp;(1203681) |  | 524613 | 1696773 | (1145671) | 551102 |
| Right of use – other assets | 240646 | (206200) |  | 34446 | 240646 | (188681) | 51965 |
| Goodwill/identifiable asset | 504910 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | 504910 |  |  |  |
| **Total** | **76860845** | **(26128350)** | **-** | **50732495** | **75940291** | **(25447818)** | **50492473** |

---

(i) With the enactment of the Basic Sanitation Law in 2007, contract renewals began to be executed through program agreements, under which the Company assumed assets and socio environmental obligations and recognized them as intangible assets, which are amortized on a straight-line basis over the term of the agreements.

**(b)** **Changes**

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025** | **Additions** | **Transfer of contract asset and other concession assets** | **Transfers** | **Write-offs and disposals** | **Amortization** | **March 31, 2026** |
| Intangible assets arising from: |  |  |  |  |  |  |  |
| Concession agreements – others | 75089 |  | 222 | (2) |  | (1048) | 74261 |
| Contract Commitments | 3730121 |  |  |  |  | (33020) | 3697101 |
| Concession Agreements URAE-1 (\*) | 45946471 |  | 388436 | 8010 | (393) | (581849) | 45760675 |
| Software license of use | 551102 |  |  |  |  | (45740) | 505362 |
| Right of use – other assets | 51968 |  |  |  |  | (17522) | 34446 |
| **Total** | **50354751** | **—** | **388658** | **8008** | **(393)** | **(679179)** | **50071845** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025** | **Additions** | **Transfer of contract asset** | **Transfers** | **Write-offs and disposals** | **Amortization** | **Business combination (Note 4)** | **March 31, 2026** |
| Intangible assets arising from: |  |  |  |  |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Concession agreements – new contracts | 137723 |  |  |  |  | (1235) |  | 136488 |
| &nbsp;&nbsp;&nbsp;Concession agreements – others | 75088 |  | 222 | (2) |  | (1048) |  | 74260 |
| &nbsp;&nbsp;&nbsp;Contract Commitments | 3730121 |  |  |  |  | (33020) |  | 3697101 |
| &nbsp;&nbsp;&nbsp;Concession Agreements URAE-1 (\*) | 45946471 |  | 388436 | 8010 | (393) | (581849) |  | 45760675 |
| &nbsp;&nbsp;&nbsp;Software license of use | 551102 |  |  |  |  | (45740) | &nbsp;&nbsp;&nbsp;&nbsp;19253 | 524615 |
| &nbsp;&nbsp;&nbsp;Right of use – other assets | 51968 |  |  |  |  | (17522) |  | 34446 |
| &nbsp;&nbsp;&nbsp;Goodwill/identifiable asset |  |  |  |  |  |  | 504910 | 504910 |
| **Total** | **50492473** | **—** | **388658** | **8008** | **(393)** | **(680414)** | **524163** | **50732495** |

---

(\*) As of March 31, 2026, the line URAE-1 concession agreement included leases totaling R$149,164 (R$154,449 as of December 31, 2025). Also on this date, the accounting balance of intangible assets, contract assets and other concession assets, and financial assets of the concession aimed at URAE-1 amounted to R$83,208,920, accounting for 95.57% of the consolidated amount.

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2024** | **Additions** | **Transfer of contract asset** | **Transfers** | **Write-offs and disposals** | **Amortization** | **Transfer to Financial Assets** | **March 31, 2025** |
| Intangible assets arising from: |  |  |  |  |  |  |  |  |
| Concession agreements – others | 59492 |  | 10 | 12 |  | (1075) |  | 58439 |
| Contract Commitments | 3849759 |  |  |  |  | (32117) |  | 3817642 |
| Concession Agreements URAE-1 (\*) | 39956194 | 1245 | 747688 | 21429 | (874) | (472288) | (168104) | 40085290 |
| Software license of use | 638287 |  | 10314 |  |  | (48338) |  | 600263 |
| Right of use – other assets | 124736 |  |  |  |  | (19127) |  | 105609 |
| **Total** | **44628468** | **1245** | **758012** | **21441** | **(874)** | **(572945)** | **(168104)** | **44667243** |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2024** | **Additions** | **Transfer of contract asset** | **Transfers** | **Write-offs and disposals** | **Amortization** | **Transfer to Financial Assets** | **March 31, 2025** |
| Intangible assets arising from: |  |  |  |  |  |  |  |  |
| Concession agreements – new contracts | 142656 |  |  |  |  | (1234) |  | 141422 |
| Concession agreements – others | 59492 |  | 10 | 12 |  | (1075) |  | 58439 |
| Contract Commitments | 3849759 |  |  |  |  | (32117) |  | 3817642 |
| Concession Agreements URAE-1 (\*) | 39956194 | 1245 | 747688 | 21429 | (874) | (472288) | (168104) | 40085290 |
| Software license of use | 638287 |  | 10314 |  |  | (48338) |  | 600263 |
| Right of use – other assets | 124736 |  |  |  |  | (19127) |  | 105609 |
| **Total** | **44771124** | **1245** | **758012** | **21441** | **(874)** | **(574179)** | **(168104)** | **44808665** |

---

(\*) As of March 31, 2025, the line URAE-1 concession agreement included leases totaling R$329,624 (R$338,740 as of December 31, 2024), respectively.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(c)** **Public-Private Partnership - PPP**

SABESP carries out transactions related to the Public-Private Partnership. Such transactions, along with their corresponding guarantees and obligations, are supported by a contract established based on Law No. 11,079/2004.

The amounts recorded in intangible assets, item Concession Agreements URAE-1, are shown in the table below:

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
| **Nature** | **March 31, 2026** | **December 31, 2025** |
| Alto Tietê | 198775 | 202823 |
| São Lourenço | 2174008 | 2216444 |

---

As of March 31, 2026, and December 31, 2025, the obligations assumed by the Company are as follows:

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Current liabilities** <br>| **Non-current liabilities** <br>| **Total liabilities** <br>| **Current liabilities** <br>| **Non-current liabilities** <br>| **Total liabilities** <br>|
| São Lourenço | 473049 | 2851931 | 3324980 | 469687 | 2856008 | 3325695 |

---

The chart below shows expenses with Public-Private Partnership from January to March 2026, compared to the figures reported in the same period in 2024:

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
| **Nature** | **January to March 2026** | **January to March 2025** |
| General supplies | 5484 | 5188 |
| Outsourced services | 11572 | 10948 |
| General expenses | 1515 | 1434 |
| Amortization | 42437 | 42437 |
| Financial expenses | 122675 | 142252 |
| **Total** | **183683** | **202259** |

---

**(d)** **Amortization of intangible assets**

The average amortization rate was 3.57% and 2.6% as of March 31, 2026 and 2025, respectively.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(e)** **Leases and right of use**

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
| **Nature** | **March 31, 2026** | **December 31, 2025** |
| Leases - Concession Agreement URAE-1 |  |  |
| Cost | 404978 | 405245 |
| Accumulated amortization | (255814) | (250796) |
| **(=) Net** | **149164** | **154449** |
| Right of use - Other assets |  |  |
| Vehicles | 216428 | 216428 |
| Properties | 24142 | 24142 |
| Equipment | 76 | 76 |
| Accumulated amortization | (206200) | (188678) |
| **(=) Net** | **34446** | **51968** |
| **Total - Leases and Right of use** | **183610** | **206417** |

---

The lease liability corresponds to total future fixed lease payments, adjusted to present value, considering an incremental rate on borrowings. For further information, see Note 17.

The table below shows the impact on the Company's profit or loss:

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **March 31, 2025** |
| Right of use amortization | (22808) | (28244) |
| Financial result – interest expense and inflation adjustment | (30922) | (38493) |
| Expenses of short-term and low-value leases | (8543) | (10533) |
| Decrease in profit for the period | **(62273)** | **(77270)** |

---

**(f)** **Performance Agreements**

The accounting balances of current agreements recorded in the contract assets and other concession assets and intangible assets are as follows:

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** |
| Contract assets and other concession assets | 405835 | 601064 |
| Intangible assets | 1089043 | 1077363 |
| Total | **1494878** | **1678427** |

---

As of March 31, 2026, and December 31, 2025, the obligations assumed by the Company are as follows:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Current liabilities**<br>| **Non-current liabilities**<br>| **Total liabilities**<br>| **Current liabilities**<br>| **Non-current liabilities**<br>| **Total liabilities**<br>|
| Performance Agreements | 125766 | 3543 | 129309 | 120776 | 6151 | 126927 |

---

**15** **Financial asset of the concession**

With the completion of the privatization process and signing of the agreement with URAE-1 in July 2024, resulting in a single agreement covering 371 municipalities with a new expiration date in 2060, which provided greater legal security and granted an unconditional right to receive cash at the end of the concession, the Company recognized a modification in the agreement, leading to a bifurcation of concession assets considering the contractual right that reversible investments and not fully amortized by the end of the agreement must be compensated.

The impacts of Income and Social Contribution Taxes and PIS and Cofins are deferred until the time of their realization.

The change in the balance of the concession's financial asset is as follows:

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025** | **Transfer of contract asset (a)** | **Financial Asset of the Concession - Restatement (b)** | **March 31, 2026** |
| Financial Asset of the Concession |  |  |  |  |
| Concession Agreement - URAE-1 | 21665330 | 118062 | 342487 | 22125879 |

---

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025** | **Transfer of contract asset (a)** | **Financial Asset of the Concession - Restatement (b)** | **Business combination (Note 4)** | **March 31, 2026** |
| Financial Asset of the Concession |  |  |  |  |  |
| Concession Agreement - URAE-1 | 21665330 | 118062 | 342487 |  | 22125879 |
| Other - EMAE |  |  |  | 195375 | 195375 |
| **Total** | **21665330** | **118062** | **342487** | **195375** | **22321254** |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **December 31, 2024** | **Transfer of contract asset (a)** | **Financial Asset of the Concession - Restatement (b)** | **March 31, 2025** |
| Financial Asset of the Concession |  |  |  |  |
| Concession Agreement - URAE-1 | 17601626 | 168104 | 420229 | 18189959 |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

(a) Correspond to transfers (bifurcation) of contract assets and other concession assets to the concession's financial asset, which were previously recognized at their cost;

(b) Review of the financial asset considering the restatement using the IPCA, as this is the rate used by the regulatory agency for the adjustment of assets to be compensated.

**16** **Property, plant, and equipment** 

&nbsp;&nbsp;&nbsp;&nbsp;**(a)** **Statement of financial position details** 

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Cost** | **Depreciation** | **Net** | **Useful life** | **Cost** | **Depreciation** | **Net** | **Useful life** |
| Land | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;101258 | &nbsp;&nbsp;&nbsp;&nbsp;(363) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;100895 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;94001 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;94001 |  |
| Buildings | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;133757 | &nbsp;&nbsp;&nbsp;&nbsp;(49843) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;83914 | 50 years | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;134818 | &nbsp;&nbsp;&nbsp;&nbsp;(49179) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;85639 | 50 years |
| Equipment | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;636363 | &nbsp;&nbsp;&nbsp;&nbsp;(356127) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;280236 | 5 - 20 years | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;629653 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(346037) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;283616 | 5 - 20 years |
| Transportation equipment | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;140475 | &nbsp;&nbsp;&nbsp;&nbsp;(21637) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;118838 | 10 years | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;126689 | &nbsp;&nbsp;&nbsp;&nbsp;(18394) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;108295 | 10 years |
| Furniture and fixtures | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;41673 | &nbsp;&nbsp;&nbsp;&nbsp;(19731) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;21942 | 15 years | &nbsp;&nbsp;&nbsp;&nbsp;41465 | &nbsp;&nbsp;&nbsp;&nbsp;(19141) | &nbsp;&nbsp;&nbsp;&nbsp;22324 | 15 years |
| Energy generation infrastructure | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;165100 | &nbsp;&nbsp;&nbsp;&nbsp;(20810) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;144290 | 15 - 20 years | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;165100 | &nbsp;&nbsp;&nbsp;&nbsp;(18084) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;147016 | 15 - 20 years |
| Other | 7279 | &nbsp;&nbsp;&nbsp;&nbsp;(666) | &nbsp;&nbsp;&nbsp;&nbsp;6613 | 20 years | &nbsp;&nbsp;&nbsp;&nbsp;7278 | &nbsp;&nbsp;&nbsp;&nbsp;(620) | &nbsp;&nbsp;&nbsp;&nbsp;6658 | 20 years |
| Property, plant and equipment in progress | 158927 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;158927 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;143242 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;143242 |  |
| **Total** | **1384832** | **(469177)** | **915655** | **—** | **1342246** | **(451455)** | **890791** | **—** |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Cost** | **Depreciation** | **Net** | **Useful life** | **Cost** | **Depreciation** | **Net** | **Useful life** |
| Land | &nbsp;&nbsp;&nbsp;&nbsp;105541 | (363) | &nbsp;&nbsp;&nbsp;&nbsp;105178 | — % | 94001 |  | &nbsp;&nbsp;&nbsp;&nbsp;94001 | —% |
| Buildings | &nbsp;&nbsp;&nbsp;&nbsp;177667 | (51024) | 126643 | 50 years | 134818 | (49179) | &nbsp;&nbsp;&nbsp;&nbsp;85639 | 50 years |
| Equipment | &nbsp;&nbsp;&nbsp;&nbsp;690270 | (358991) | &nbsp;&nbsp;&nbsp;&nbsp;331279 | 5 - 20 years | 629653 | (346037) | &nbsp;&nbsp;&nbsp;&nbsp;283616 | 5 - 20 years |
| Transportation equipment | &nbsp;&nbsp;&nbsp;&nbsp;140555 | (21645) | &nbsp;&nbsp;&nbsp;&nbsp;118910 | 10 years | 126689 | (18394) | &nbsp;&nbsp;&nbsp;&nbsp;108295 | 10 years |
| Furniture and fixtures | &nbsp;&nbsp;&nbsp;&nbsp;41968 | (19761) | 22207 | 15 years | 41465 | (19141) | &nbsp;&nbsp;&nbsp;&nbsp;22324 | 15 years |
| Energy generation infrastructure | &nbsp;&nbsp;&nbsp;&nbsp;165100 | (20810) | 144290 | 15 - 20 years | 165100 | (18084) | &nbsp;&nbsp;&nbsp;&nbsp;147016 | 15 - 20 years |
| Reservoirs, dams and pipelines | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;40845 | (1071) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;39774 | 50 years |  |  |  | —% |
| Other | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;16709 | (823) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;15886 | 20 years | 7278 | (620) | &nbsp;&nbsp;&nbsp;&nbsp;6658 | 20 years |
| Property, plant and equipment in progress | &nbsp;&nbsp;&nbsp;&nbsp;231045 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(10449) | 220596 | — % | 143242 |  | &nbsp;&nbsp;&nbsp;&nbsp;143242 | —% |
| **Total** | **1609700** | **(484937)** | **1124763** | **—** | **1342246** | **(451455)** | **890791** | **—** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

&nbsp;&nbsp;&nbsp;&nbsp;**(b)** **Changes** 

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025** | **Additions** | **Transfers** | **Write-offs and disposals** | **Depreciation** | **March 31, 2026** |
| Land | 94001 |  | 6894 |  |  | 100895 |
| Buildings | 85639 |  | (18) | (1149) | (558) | 83914 |
| Equipment | 283616 |  | 6521 | (36) | (9865) | 280236 |
| Transportation equipment | 108295 |  | 13835 | (9) | (3283) | 118838 |
| Furniture and fixtures | 22324 |  | 199 |  | (581) | 21942 |
| Energy generation infrastructure | 147016 |  |  |  | (2726) | 144290 |
| Other | 6658 |  |  |  | (45) | 6613 |
| Property, plant and equipment in progress | 143242 | 33955 | (18270) | - | - | 158927 |
| **Total** | **890791** | **33955** | **9161** | **(1194)** | **(17058)** | **915655** |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025** | **Additions** | **Transfers** | **Write-offs and disposals** | **Depreciation** | **Business combination (Note 4)** | **March 31, 2026** |
| Land | 94001 |  | 6894 |  |  | 4283 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;105178 |
| Buildings | 85639 |  | (18) | (1149) | (558) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;42279 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;126643 |
| Equipment | 283616 |  | 6521 | (36) | (9865) | 51043 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;331279 |
| Transportation equipment | 108295 |  | 13835 | (9) | (3283) | 72 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;118910 |
| Furniture and fixtures | 22324 |  | &nbsp;&nbsp;&nbsp;&nbsp;199 |  | (581) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;265 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;22207 |
| Energy generation infrastructure | 147016 |  |  |  | (2726) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;144290 |
| Reservoirs, dams and pipelines |  |  |  |  |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;39774 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;39774 |
| Other | 6658 |  |  |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (45) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9273 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;15886 |
| Property, plant and equipment in progress | 143242 | 33955 | &nbsp;&nbsp;&nbsp;&nbsp; <br> (18270)  |  |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;61669 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;220596 |
| **Total** | **890791** | **33955** | **9161** | **(1194)** | **(17058)** | **209108** | **1124763** |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **December 31, 2024** | **Additions** | **Transfers** | **Write-offs and disposals** | **Depreciation** | **March 31, 2025** |
| Land | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;94751 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;62 | (33) |  |  | &nbsp;&nbsp;&nbsp;&nbsp;94780 |
| Buildings | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;80920 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;209 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(527) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;80602 |
| Equipment | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;149744 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;9636 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(54) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(5332) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;153994 |
| Transportation equipment | 23538 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;19807 |  | &nbsp;&nbsp;&nbsp;&nbsp;(826) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;42519 |
| Furniture and fixtures | &nbsp;&nbsp;&nbsp;&nbsp;20779 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;1724 | (6) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(549) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;21948 |
| Energy generation infrastructure | &nbsp;&nbsp;&nbsp;&nbsp;121533 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br> - | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5 |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2096) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;119442 |
| Other | &nbsp;&nbsp;&nbsp;&nbsp;6930 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(48) | &nbsp;&nbsp;&nbsp;&nbsp;6882 |
| Property, plant and equipment in progress | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;63353 | 60674 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(26320) |  |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;97707 |
| **Total** | **561548** | **60736** | **5028** | **(60)** | **(9378)** | **617874** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | |
|:---|:---|
| **17** | **Borrowings and financing** |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
| **Borrowings and financing outstanding balance** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
| **Financial institution** | **Current** | **Non-current** | **Total** | **Current** | **Non-current** | **Total** |
| **Local currency** |  |  |  |  |  |  |
| &nbsp;&nbsp;Debentures | 2768889 | 25637595 | 28406484 | 2764582 | 20230117 | 22994699 |
| &nbsp;&nbsp;Brazilian Federal Savings Bank | 137030 | 1467440 | 1604470 | 134275 | 1495481 | 1629756 |
| &nbsp;&nbsp;BNDES | 259709 | 504300 | 764009 | 259341 | 564501 | 823842 |
| &nbsp;&nbsp;IDB | 298509 | 2554865 | 2853374 | 307349 | 2680484 | 2987833 |
| &nbsp;&nbsp;IFC | 22650 | 2006802 | 2029452 | 64450 | 2645882 | 2710332 |
| &nbsp;&nbsp;Leases (Concession) | 74650 | 110178 | 184828 | 84214 | 110214 | 194428 |
| &nbsp;&nbsp;Leases (Other) | 70172 | 7724 | 77896 | 72440 | 9627 | 82067 |
| &nbsp;&nbsp;Other | 483 | 725 | 1208 | 616 | 328 | 944 |
| &nbsp;&nbsp;Interest | 848930 |  | 848930 | 1139091 |  | 1139091 |
| **Total in local currency** | **4481022** | **32289629** | **36770651** | **4826358** | **27736634** | **32562992** |
| **Foreign currency** |  |  |  |  |  |  |
| &nbsp;&nbsp;IDB | 53661 | 904542 | 958203 | 56573 | 973833 | 1030406 |
| &nbsp;&nbsp;IBRD | 31731 | 1011545 | 1043276 | 33453 | 1112127 | 1145580 |
| &nbsp;&nbsp;JICA | 140783 | 1732536 | 1873319 | 150779 | 1965688 | 2116467 |
| &nbsp;&nbsp;IFC |  | 3158572 | 3158572 |  | 3380431 | 3380431 |
| &nbsp;&nbsp;A/B Blue Bonds |  | 8017482 | 8017482 |  |  |  |
| &nbsp;&nbsp;Interest | 176930 |  | 176930 | 65727 |  | 65727 |
| **Total in foreign currency** | **403105** | **14824677** | **15227782** | **306532** | **7432079** | **7738611** |
| **Total borrowings and financing** | **4884127** | **47114306** | **51998433** | **5132890** | **35168713** | **40301603** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
| **Borrowings and financing outstanding balance** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
| **Financial institution** | **Current** | **Non-current** | **Total** | **Current** | **Non-current** | **Total** |
| **Local currency** |  |  |  |  |  |  |
| &nbsp;&nbsp;Debentures | 2768889 | &nbsp;&nbsp;&nbsp;&nbsp;22655074 | &nbsp;&nbsp;&nbsp;&nbsp;25423963 | &nbsp;&nbsp;&nbsp;&nbsp;2764582 | &nbsp;&nbsp;&nbsp;&nbsp;17282427 | &nbsp;&nbsp;&nbsp;&nbsp;20047009 |
| &nbsp;&nbsp;Brazilian Federal Savings Bank | 137030 | &nbsp;&nbsp;&nbsp;&nbsp;1, 467440 | &nbsp;&nbsp;&nbsp;&nbsp;1604470 | &nbsp;&nbsp;&nbsp;&nbsp;134275 | &nbsp;&nbsp;&nbsp;&nbsp;1495481 | &nbsp;&nbsp;&nbsp;&nbsp;1629756 |
| &nbsp;&nbsp;BNDES | 259709 | &nbsp;&nbsp;&nbsp;&nbsp;504300 | &nbsp;&nbsp;&nbsp;&nbsp;764009 | &nbsp;&nbsp;&nbsp;&nbsp;259341 | 564501 | &nbsp;&nbsp;&nbsp;&nbsp;823842 |
| &nbsp;&nbsp;IDB | 298509 | &nbsp;&nbsp;&nbsp;&nbsp;2554865 | &nbsp;&nbsp;&nbsp;&nbsp;2853374 | &nbsp;&nbsp;&nbsp;&nbsp;307349 | &nbsp;&nbsp;&nbsp;&nbsp;2680484 | &nbsp;&nbsp;&nbsp;&nbsp;2987833 |
| &nbsp;&nbsp;IFC | 22650 | &nbsp;&nbsp;&nbsp;&nbsp;2006802 | &nbsp;&nbsp;&nbsp;&nbsp;2029452 | &nbsp;&nbsp;&nbsp;&nbsp;64450 | &nbsp;&nbsp;&nbsp;&nbsp;2645882 | &nbsp;&nbsp;&nbsp;&nbsp;2710332 |
| &nbsp;&nbsp;Leases (Concession) | 74650 | 110178 | 184828 | &nbsp;&nbsp;&nbsp;&nbsp;84214 | 110214 | &nbsp;&nbsp;&nbsp;&nbsp;194428 |
| &nbsp;&nbsp;Leases (Other) | 70620 | 11256 | &nbsp;&nbsp;&nbsp;&nbsp;1876 | &nbsp;&nbsp;&nbsp;&nbsp;72440 | 9627 | &nbsp;&nbsp;&nbsp;&nbsp;82067 |
| &nbsp;&nbsp;Other | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;483 | 727 | 1210 | 616 | 328 | 944 |
| &nbsp;&nbsp;Interest | 819813 |  | 819813 | &nbsp;&nbsp;&nbsp;&nbsp;1033884 |  | &nbsp;&nbsp;&nbsp;&nbsp;1033884 |
| **Total in local currency** | **4452353** | **29310642** | **33762995** | **4721151** | **24788944** | **29510095** |
| **Foreign currency** |  |  |  |  |  |  |
| &nbsp;&nbsp;IDB | &nbsp;&nbsp;&nbsp;&nbsp;53661 | &nbsp;&nbsp;&nbsp;&nbsp;904542 | 958203 | 56573 | 973833 | &nbsp;&nbsp;&nbsp;&nbsp;1030406 |
| &nbsp;&nbsp;IBRD | &nbsp;&nbsp;&nbsp;&nbsp;31731 | &nbsp;&nbsp;&nbsp;&nbsp;1011545 | 1043276 | 33453 | 1112127 | &nbsp;&nbsp;&nbsp;&nbsp;1145580 |
| &nbsp;&nbsp;JICA | &nbsp;&nbsp;&nbsp;&nbsp;140783 | &nbsp;&nbsp;&nbsp;&nbsp;1732536 | 1873319 | &nbsp;&nbsp;&nbsp;&nbsp;150779 | &nbsp;&nbsp;&nbsp;&nbsp;1965688 | &nbsp;&nbsp;&nbsp;&nbsp;2116467 |
| &nbsp;&nbsp;IFC |  | &nbsp;&nbsp;&nbsp;&nbsp;3158572 | 3158572 |  | &nbsp;&nbsp;&nbsp;&nbsp;3380431 | &nbsp;&nbsp;&nbsp;&nbsp;3380431 |
| &nbsp;&nbsp;A/B Blue Bonds |  | &nbsp;&nbsp;&nbsp;&nbsp;8017481 | 8017481 |  |  |  |
| &nbsp;&nbsp;Blue Bonds |  | &nbsp;&nbsp;&nbsp;&nbsp;2634627 | 2634627 |  | &nbsp;&nbsp;&nbsp;&nbsp;2828508 | &nbsp;&nbsp;&nbsp;&nbsp;2828508 |
| &nbsp;&nbsp;Interest | &nbsp;&nbsp;&nbsp;&nbsp;194152 | - | 194152 | &nbsp;&nbsp;&nbsp;&nbsp;130860 | - | &nbsp;&nbsp;&nbsp;&nbsp;130860 |
| **Total in foreign currency** | **420327** | **17459303** | **17879630** | **371665** | **10260587** | **10632252** |
| **Total borrowings and financing** | **4872680** | **46769945** | **51642625** | **5092816** | **35049531** | **40142347** |

---

Quotes as of March 31, 2026: US$ – R$5.2194; Yen – R$0.03281; EUR - R$6.0117 (as of December 31, 2025: US$ – R$5.5024; Yen – R$0.03514; Euro – R$6.4692).

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(i)** **Payment schedule – accounting balances as of March 31, 2026**

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
| **Payment Schedule** | **April to** <br> **December,** <br> **2026** | **2027** | **2028** | **2029** | **2030** | **2031** | **2032 to 2048** | **Total** |
| **Local currency** |  |  |  |  |  |  |  |  |
| Debentures | 2768889 | 1200338 | 442804 | 1102764 | 4544479 | 3218427 | 15128783 | 28406484 |
| Brazilian Federal Savings Bank | 101938 | 143304 | 152093 | 158155 | 155850 | 141735 | 751395 | 1604470 |
| BNDES | 195358 | 247853 | 87849 | 35575 | 35575 | 35575 | 126224 | 764009 |
| IDB | 172474 | 289669 | 359999 | 330039 | 265949 | 265949 | 1169295 | 2853374 |
| IFC | 22650 | 30600 | 63850 | 97100 | 183000 | 407800 | 1224452 | 2029452 |
| Leases | 69079 | 8429 | 17812 | 23673 | 12563 | 19821 | 111347 | 262724 |
| Other | 363 | 484 | 361 |  |  |  |  | 1208 |
| Interest and Other Charges | 848930 |  |  |  |  |  |  | 848930 |
| **Total in local currency** | **4179681** | **1920677** | **1124768** | **1747306** | **5197416** | **4089307** | **18511496** | **36770651** |
| **Foreign currency** |  |  |  |  |  |  |  |  |
| IDB | 53663 | 53663 | 53663 | 53663 | 53663 | 53663 | 636225 | 958203 |
| IBRD | 15866 | 31732 | 31732 | 74267 | 74267 | 74267 | 741145 | 1043276 |
| JICA | 75127 | 187634 | 234487 | 234487 | 162679 | 162679 | 816226 | 1873319 |
| IFC |  |  |  | 1574682 | 1574682 |  | 9208 | 3158572 |
| Bonds - Sabesp |  |  |  |  |  | 4436490 | 3580992 | 8017482 |
| Interest and Other Charges | 176930 |  |  |  |  |  |  | 176930 |
| **Total in foreign currency** | **321586** | **273029** | **319882** | **1937099** | **1865291** | **4727099** | **5783796** | **15227782** |
| **Total** | **4501267** | **2193706** | **1444650** | **3684405** | **7062707** | **8816406** | **24295292** | **51998433** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
| **Payment Schedule** | **April to** <br> **December,** <br> **2026** | **2027** | **2028** | **2029** | **2030** | **2031** | **2032 to 2048** | **Total** |
| **Local currency** |  |  |  |  |  |  |  |  |
| &nbsp;&nbsp;Debentures | 2768889 | 1200338 | 442804 | 1102764 | 1561958 | 3218427 | 15128783 | 25423963 |
| &nbsp;&nbsp;Brazilian Federal Savings Bank | 101938 | 143304 | 152093 | 158155 | 155850 | 141735 | 751395 | 1604470 |
| &nbsp;&nbsp;BNDES | 195358 | 247853 | 87849 | 35575 | 35575 | 35575 | 126224 | 764009 |
| &nbsp;&nbsp;IDB | 172474 | 289669 | 359999 | 330039 | 265949 | 265949 | 1169295 | 2853374 |
| &nbsp;&nbsp;IFC | 22650 | 30600 | 63850 | 97100 | 183000 | 407800 | 1224452 | 2029452 |
| &nbsp;&nbsp;Leases | 69891 | 9481 | 18740 | 24490 | 12934 | 19821 | 111347 | 266704 |
| &nbsp;&nbsp;Other | 363 | 484 | 363 |  |  |  |  | 1210 |
| &nbsp;&nbsp;Interest and Other Charges | 819813 | - | - | - | - | - | - | 819813 |
| **Total in local currency** | **4151376** | **1921729** | **1125698** | **1748123** | **2215266** | **4089307** | **18511496** | **33762995** |
| **Foreign currency** |  |  |  |  |  |  |  |  |
| &nbsp;&nbsp;IDB | 53663 | 53663 | 53663 | 53663 | 53663 | 53663 | 636225 | 958203 |
| &nbsp;&nbsp;IBRD | 15866 | 31732 | 31732 | 74267 | 74267 | 74267 | 741145 | 1043276 |
| &nbsp;&nbsp;JICA | 75127 | 187634 | 234487 | 234487 | 162679 | 162679 | 816226 | 1873319 |
| &nbsp;&nbsp;IFC |  |  |  | 1574682 | 1574682 |  | 9208 | 3158572 |
| &nbsp;&nbsp;*Bonds - Sabesp* |  |  |  |  |  | 4436490 | 3580991 | 8017481 |
| &nbsp;&nbsp;*Blue Bonds* |  |  |  |  | 2634627 |  |  | 2634627 |
| &nbsp;&nbsp;Interest and Other Charges | 194152 | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;- | - | - | - | 194152 |
| **Total in foreign currency** | **338808** | **273029** | **319882** | **1937099** | **4499918** | **4727099** | **5783795** | **17879630** |
| **Total** | **4490184** | **2194758** | **1445580** | **3685222** | **6715184** | **8816406** | **24295291** | **51642625** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

(ii) **Changes**

---

| | | | | | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Changes** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025** | **Funding** | **Borrowing costs** | **Inflation** **adjustment and exchange rate changes** | **Inflation adjustment/Exchange rate change - Capitalized** | **Interest Paid** | **Amortization** | **Accrued interest** | **Provision for interest and charges -<br> capitalized** | **Expenses with borrowing costs** | **Other changes** | **Fair value** | **March 31, 2026** |
| **Local currency** |  |  |  |  |  |  |  |  |  |  |  |  |  |
| Debentures | 23920841 | 6292086 | (152922) | 170288 | 3425 | (992615) | (500000) | 525342 | 174181 | 9562 |  | (410654) | 29039534 |
| Brazilian Federal Savings Bank | 1634323 |  |  | 8944 | 694 | (31419) | (34926) | 29191 | 2194 |  |  |  | 1609001 |
| BNDES | 826580 |  |  | 5302 | 644 | (15481) | (65890) | 13569 | 1551 | 110 |  |  | 766385 |
| IDB | 3136210 |  |  |  |  | (161704) | (134874) | 89240 | 21564 | 416 |  |  | 2950852 |
| IFC | 2767605 |  |  |  |  | (32811) | (687800) | 66629 | 20405 | 6921 |  |  | 2140949 |
| Leases (Concession) | 194427 |  |  |  |  |  | (30562) | 20963 |  |  |  |  | 184828 |
| Leases (Other) | 82068 |  |  |  |  |  | (12154) | 7981 |  |  |  |  | 77895 |
| Other | 938 | 768 |  |  |  | (8) | (500) | 8 | 1 |  |  |  | 1207 |
| **Total in local currency** | **32562992** | **6292854** | **(152922)** | **184534** | **4763** | **(1234038)** | **(1466706)** | **752923** | **219896** | **17009** | **—** | **(410654)** | **36770651** |
| **Foreign currency** |  |  |  |  |  |  |  |  |  |  |  |  |  |
| IDB | 1037182 |  | (78) | (56694) | 2866 |  |  | 10581 | 1773 | 399 |  | (18696) | 977333 |
| IBRD | 1160707 |  | (782) | (59667) |  | (25665) | (15823) | 12801 |  | 190 |  | (26221) | 1045540 |
| JICA | 2125285 |  |  | (143121) | (421) | (8413) | (67730) | 8582 | 34 | 269 |  | (32146) | 1882339 |
| IFC | 3415437 |  |  | (199700) |  |  |  | 31619 | 4890 | 946 |  | (23105) | 3230087 |
| A/B Blue Bonds |  | 7845150 | (111121) | (16050) |  |  |  | 75002 |  | 1425 |  | 298077 | 8092483 |
| **Total in foreign currency** | **7738611** | **7845150** | **(111981)** | **(475232)** | **2445** | **(34078)** | **(83553)** | **138585** | **6697** | **3229** | **—** | **197909** | **15227782** |
| **Total** | **40301603** | **14138004** | **(264903)** | **(290698)** | **7208** | **(1268116)** | **(1550259)** | **891508** | **226593** | **20238** | **—** | **(212745)** | **51998433** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Changes** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025** | **Funding** | **Borrowing costs** | **Inflation adjustment and exchange rate changes** | **Inflation adjustment/Exchange rate change - Capitalized** | **Interest Paid** | **Amortization** | **Accrued interest** | **Provision for interest and charges -<br> capitalized** | **Expenses with borrowing costs** | **Other changes** | **Fair value** | **March 31, 2026** |
| **Local currency** |  |  |  |  |  |  |  |  |  |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Debentures | 20867944 | 6292086 | (152922) | 126710 | 3425 | (853898) | (500000) | 462715 | 174181 | 9570 |  | (401914) | 26027897 |
| &nbsp;&nbsp;&nbsp;Brazilian Federal Savings Bank | 1634323 |  |  | 8944 | 694 | (31419) | (34926) | 29191 | 2194 |  |  |  | 1609001 |
| &nbsp;&nbsp;&nbsp;BNDES | 826580 |  |  | 5302 | 644 | (15481) | (65890) | 13569 | 1551 | 110 |  |  | 766385 |
| &nbsp;&nbsp;&nbsp;IDB | 3136210 |  |  |  |  | (161704) | (134874) | 89240 | 21564 | 416 |  |  | 2950852 |
| &nbsp;&nbsp;&nbsp;IFC | 2767605 |  |  |  |  | (32811) | (687800) | 66629 | 20405 | 6921 |  |  | 2140949 |
| &nbsp;&nbsp;&nbsp;Leases (Concession) | 194427 |  |  |  |  |  | (30562) | 20963 |  |  |  |  | 184828 |
| &nbsp;&nbsp;&nbsp;Leases (Other) | 82068 |  |  |  |  |  | (12154) | 7981 |  |  | 3981 |  | 81876 |
| &nbsp;&nbsp;&nbsp;Other | 938 | 768 |  |  |  | (8) | (500) | 8 | 1 |  |  |  | 1207 |
| **Total in local currency** | **29510095** | **6292854** | **(152922)** | **140956** | **4763** | **(1095321)** | **(1466706)** | **690296** | **219896** | **17017** | **3981** | **(401914)** | **33762995** |
| **Foreign currency** |  |  |  |  |  |  |  |  |  |  |  |  |  |
| &nbsp;&nbsp;&nbsp;IDB | 1037182 |  | (78) | (56694) | 2866 |  |  | 10581 | 1773 | 399 |  | (18696) | 977333 |
| &nbsp;&nbsp;&nbsp;IBRD | 1160707 |  | (782) | (59667) |  | (25665) | (15823) | 12801 |  | 190 |  | (26221) | 1045540 |
| &nbsp;&nbsp;&nbsp;JICA | 2125285 |  |  | (143121) | (421) | (8413) | (67730) | 8582 | 34 | 269 |  | (32146) | 1882339 |
| &nbsp;&nbsp;&nbsp;IFC | 3415437 |  |  | (199700) |  |  |  | 31619 | 4890 | 946 |  | (23105) | 3230087 |
| &nbsp;&nbsp;&nbsp;A/B Blue Bonds |  | 7845150 | (111121) | (16050) |  |  |  | 75002 |  | 1425 |  | 298077 | 8092483 |
| &nbsp;&nbsp;&nbsp;*Blue Bonds* | 2893641 |  |  | (148825) |  | (81555) |  | 36994 |  | 966 |  | (49373) | 2651848 |
| **Total in foreign currency** | **10632252** | **7845150** | **(111981)** | **(624057)** | **2445** | **(115633)** | **(83553)** | **175579** | **6697** | **4195** | **—** | **148536** | **17879630** |
| **Total** | **40142347** | **14138004** | **(264903)** | **(483101)** | **7208** | **(1210954)** | **(1550259)** | **865875** | **226593** | **21212** | **3981** | **(253378)** | **51642625** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

&nbsp;&nbsp;&nbsp;&nbsp;**(a)** **Main events in the period ended March 31, 2026** 

**38th Debenture Issue**

In March, the Company raised R$6,292 million from the issue of simple unsecured non-convertible debentures, in five series, with the following characteristics:

---

| | | | | |
|:---|:---|:---|:---|:---|
| **Instrument** | **Amount** | **Rate** | **Maturity** | **Hedge Cost** |
| 38th issue - 1st series | 1635679 | IPCA + 6.2907% | 2036 | DI - 1.38%% a |
| 38th issue - 2nd series | 1364730 | IPCA + 6.3507% | 2038 | DI - 1.26%% a |
| 38th issue - 3rd series | 1291677 | IPCA + 6.2467% | 2041 | DI - 1.40%% a |
| 38th issue - 4th series | 1000000 | DI +0.64% | 2033 | - |
| 38th issue - 5th series | 1000000 | DI +0.72% | 2036 | - |
| **Total** | **6292086** |  |  |  |

---

The agreed covenants are:

- Disposal of operating assets, termination of license or loss of concession that, considered alone or together during the term of the agreement, result in a reduction in the Company's net sales and/or services revenue of more than twenty-five percent (25%). The above limit will be calculated every year, taking into consideration the Company's net operating income for the year immediately prior and using the financial information disclosed by the Company. Failure to comply with the limit above constitutes a default event that may lead to the early maturity of the Debentures.

**A/B Blue Bonds**

In February 2026, the Company contracted financing with the Inter-American Investment Corporation, in the total amount of US$1,500 million, with the following characteristics:

---

| | | | | | |
|:---|:---|:---|:---|:---|:---|
| **Instrument** | **Amount**<br> **Currency of Origin** | **Amount (R$)** | **Rate** | **Hedge Cost** | **Maturity** |
| AB BOND 5Y | 850000 | 4445585 | 5.75% | DI + 1.24% p.a. | 2031 |
| AB BOND 10Y | 500000 | 2615050 | 6.5% | DI + 1.99% p.a. | 2036 |
| AB BOND 12Y | 150000 | 784515 | SOFR + 2.75% | (i) | 2038 |
| **Total** | **1500000** |  |  |  |  |

---

(i) A Non-Deliverable Forward ("NDF") derivative instrument was preliminarily contracted as a pre-hedge for the purpose of hedging the currency exchange variation of the aforementioned bond. Subsequently, the Company will contract a swap derivative instrument, converting the debt indexed to SOFR + 2.75% into DI+.

There are no financial covenants associated with these financing agreements.

**(b)** **Leases**

The Company has lease agreements signed as Assets Lease. During the construction period, work costs are capitalized to contract assets against the lease liability.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

The amounts payable for the right of use of assets are also recorded in this line. See Note 14 (e).

**(c)** **Covenants**

The table below presents the claused containing the most restrictive covenants as of March 31, 2026.

---

| | |
|:---|:---|
|  | **Covenants** |
| Adjusted EBITDA/Adjusted Financial Expense | Equal to or higher than 3.50 |
| Adjusted EBITDA /Financial Expense Paid | Equal to or higher than 2.35 |
| Adjusted Net Debt/Adjusted EBITDA | Equal to or less than 3.00 |
| Net Debt /Adjusted EBITDA | Equal to or less than 3.50 |
| Other Onerous Debts <sup>(1)</sup>/Adjusted EBITDA | Equal to or less than 1.00 |

---

<sup>(1)</sup> The contractual definition of "Other Onerous Debts" corresponds to the sum of pension obligations and healthcare plan, installment payment of tax debts, and installment payment of debts with the electricity supplier.

As of March 31, 2026, and December 31, 2025, the Company met the requirements outlined by its borrowings and financing agreements.

**(d)** **Borrowings and financing contracted and not yet used**

---

| | |
|:---|:---|
| | **Individual and Consolidated** |
| **Agent** | **March 31, 2026** |
|  | (in millions of Reais (\*)) |
| Brazilian Federal Savings Bank | 703 |
| Inter-American Development Bank - IDB | 547 |
| International Bank for Reconstruction and Development – IBRD | 475 |
| Banco BTG Pactual | 949 |
| Other | 4 |
| **Total** | **2678** |

---

(\*) Brazilian Central Bank's exchange rate as of March 31, 2026 (US$1.00 = R$5.2194).

The funds from financing contracted have specific purposes and are released for the execution of their respective investments, according to the execution of the works.

**(e)** **General information**

Below is detailed information on the borrowings and financing in force as of March 31, 2026. For a better understanding, the table below consolidates the instruments by financial institution, remuneration, currency of origin and linked guarantees:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
|  **Financial institution/**<br> **Instrument** | **Guarantees** | **Final maturity** | **Annual interest rate** | **Currency** |
| Inter-American Development Bank |  | 2029 – 2036 | CDI + 0.30% to 1.50% | Real |
| Inter-American Development Bank | Federal Government | 2044 | SOFR + 1.21% | Dollar |
| Inter-American Development Bank | Federal Government | 2035 | CDI+ 0.86 | Real |
| International Finance Corporation |  | 2030 | SOFR + 1.80% | Dollar |
| International Finance Corporation |  | 2030 | EURIBOR + 1.85% | Euro |
| International Finance Corporation |  | 2033 - 2034 | CDI+0.2735% to 1.70% | Real |
| International Bank for Reconstruction and Development | Federal Government | 2034 - 2048 | SOFR + 0.74% and 1.84% | Dollar |
| JICA | Federal Government | 2029 - 2037 | 0.01% - 2.50% | Yen |
| JICA |  | 2037 | 2.00%. | Yen |
| Debentures |  | 2026 - 2040 | CDI + 0.00% to 1.60% | Real |
| Debentures |  | 2026 - 2041 | IPCA + 3.20% to 7.38% | Real |
| Brazilian Federal Savings Bank | Receivables | 2027 – 2042 | TR + 5,0% to 8.0% | Real |
| Brazilian Development Bank | Receivables | 2026 – 2035 | TJLP + 1.66% to 2.18% | Real |
| Blue Senior Unsecured Notes ("Blue Bonds") |  | 2030 | 5.62% | Dollar |
| Fehidro |  | 2028 | 3.00% | Real |
| A/B Blue Bond |  | 2031-2036 | 5.75% to 6.5% | Dollar |
| A/B Blue Bond |  | 2038 | SOFR + 2.75% | Dollar |
| Leases |  | 2035 | IPCA + 7.73% to 10.12% | Real |
| Leases |  | 2042 | 9.74% to 15.24% | Real |

---

**18** **Financial instruments**

As of March 31, 2026, the Company had financial assets classified as amortized cost and fair value through profit or loss.

The financial instruments included in the amortized cost category comprise cash and cash equivalents, financial investments, restricted cash, trade receivables, balances with related parties, registered warrants, other assets and balances receivable from the Water National Agency (ANA), financial assets of the concession, trade payables, borrowings and financing in local and foreign currency (except for those irrevocably designated at fair value through profit or loss, in accordance with Note 19), services payable, and balances payable deriving from the Public-Private Partnership (PPP), which are non-derivative financial assets and liabilities with fixed or determinable payments, not quoted in an active market, except for cash equivalents and financial investments.

Additionally, SABESP has financial assets receivable from related parties, totaling R$1,128,255 as of March 31, 2026 (R$1,139,064 as of December 31, 2025), which were calculated under the conditions negotiated between the related parties. The conditions and additional information related to these financial instruments are disclosed in Note 11. Part of this balance, totaling R$997,978 (R$1,016,69 as of December 31, 2025), refers to reimbursement of additional retirement and pension plan - G0, indexed to the IPCA plus simple interest of 0.5% p.m. On the transaction date, this interest rate approximated that of National Treasury Notes (NTN-b), with a term similar to the terms of related-party transactions.

Considering the nature of other financial instruments, assets and liabilities, the balances recognized in the statement of financial position approximate the fair values, except for borrowings and financing, considering (i) the maturities close to the end of the reporting date of the financial statements, (ii) comparison of contractual interest rates with market rates in similar transactions at the end of the reporting periods, and (iii) their nature, and maturity terms.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Carrying amount** | **Fair value** | **Carrying amount** | **Fair value** | **Carrying amount** | **Fair value** | **Carrying amount** | **Fair value** |
| Borrowings and financing | 51998433 | 52259682 | 51642625 | 51916605 | 40301603 | 40360558 | 40142347 | 40376452 |

---

The criteria adopted to obtain the fair values of borrowings and financing in preparing the quarterly information as of March 31, 2026, are consistent with those used in the preparation of the Annual Financial Statements for the fiscal year ended December 31, 2025.

Financial instruments referring to, borrowings and financing, and derivative financial instruments are classified as Level 2 in the fair value hierarchy and there were no transfers between levels during this period.

There are no instruments classified as level 1 or level 3.

**19** **Derivative financial instruments and hedging transactions**

The Company is exposed to certain risks related to its transactions. The main risks managed with derivative instruments are currency risk and interest rate risk.

The Company's risk management strategy and how it is applied is disclosed in Note 5.1 above, applicable to consolidated balances. As of March 31, 2026, regarding derivative transactions, the Company held a liability position of R$1,484,755 (Consolidated) and R$1.142.171 (Individual) (as of December 31, 2025, a liability position of R$521,832 (Consolidated) and R$661.421 (Individual)).

**Derivatives designated as hedging instruments**

<u>Fair value hedges</u>

As of March 31, 2026, the Company had an interest rate and currency swap agreement with a notional value of Yen 36 billion, US$761 million and Euro 220 million (Yen 36 billion, US$761 million, and Euro 220 million as of December 31, 2025), which provides that the Company will receive fixed and variable interest rates and pay a variable rate equal to the DI rate plus or less an interest percentage. Swaps are used to hedge exposure to changes in the fair value of loans and financing.

There is an economic relationship between the hedged items and the hedging instruments, since the terms of the swaps correspond to the terms of the loans and financing transactions (for example, the notional amount, ratios and the maturity date). To test the effectiveness of fair value hedging transactions, the Company uses the critical terms match method in order to assess whether all terms of the derivative are in line with the terms of the hedged item, in relation to terms, amortizations, contractual notional value, and interest payment.

The potential sources of hedge ineffectiveness evaluated by the Company are:

&nbsp;&nbsp;&nbsp;&nbsp;• Differences in the timing of cash flows from
hedged items and hedging instruments.

&nbsp;&nbsp;&nbsp;&nbsp;• Different ratios (and, consequently, different
curves) associated with the hedged risk of the hedged items and hedging instruments.

&nbsp;&nbsp;&nbsp;&nbsp;• Counterparties' credit risk has a different
impact on the fair value changes of hedging instruments and hedged items.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

The effect of the fair value hedge on the statements of financial position and income statement as of March 31, 2026, is shown below:

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
| **Transactions** | **Currency/ Index** | **Financing** | **Notional Value** | **Fair Value of Asset Position** | **Fair Value of Liability Position** | **Accumulated Gain / (Loss) on Derivatives - Swap** | **Gain / (Loss) on 2025 Derivatives for the period** | **Gain / (Loss) on Fair value on the hedged item** |
| 1 | Yen | Cross-currency swap | 36787581 | 942456 | 1201272 | (258816) | (124762) | 12276 |
| 2 | Euro | Cross currency swap | 220000 | 1375154 | 1546433 | (171279) | (145354) | 6303 |
| 3 | Dollar | Cross-currency swap | 761261 | 3968174 | 4564284 | (596110) | (376632) | 61719 |
| **Total** | **Total** | **Total** |  | **6285784** | **7311989** | **(1026205)** | **(646748)** | **80298** |

---

**Derivatives not designated as hedging instruments**

As of March 31, 2026, the Company had an interest rate swap, which provides that the Company will receive fixed and variable interest rates and pay a variable rate equal to the DI rate plus or less an interest percentage.

These derivatives were not designated to documented hedge accounting structures, and the Company chose to irrevocably designate the hedged liabilities to the fair value option in order to reduce accounting mismatches.

The effect of derivatives not designated to hedge accounting, as well as of liabilities selected at the fair value option on the statement of financial position and income statement is shown below:

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
| **Transactions** | **Currency/ Index** | **Financing** | **Notional Value** | **Fair Value of Asset Position** | **Fair Value of Liability Position** | **Accumulated Gain / (Loss) on Derivatives - Swap** | **Gain / (Loss) on 2025 Derivatives for the period** | **Gain / (Loss) on Fair value on the hedged item** |
| 1 | IPCA | Interest rate swap | 10807786 | 10948800 | 10694955 | 253845 | (35343) | 410654 |
| 2 | Yen | Cross currency swap | 30000000 | 930240 | 1048553 | (118313) | (120029) | 19870 |
| 3 | Dollar | Cross currency swap | 1500000 | 7410474 | 7654999 | (244525) | (244525) | (298077) |
| 4 | Dollar | Non-Deliverable Forward | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;150000 |  |  | (6973) | (86261) |  |
| **Total** |  |  |  | **19289514** | **19398507** | **(115966)** | **(486158)** | **132447** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
| **Transactions** | **Currency/ Index** | **Financing** | **Notional Value** | **Fair Value of Asset Position** | **Fair Value of Liability Position** | **Accumulated Gain / (Loss) on Derivatives - Swap** | **Gain / (Loss) on 2025 Derivatives for the period** | **Gain / (Loss) on Fair value on the hedged item** |
| 1 | IPCA | Interest rate swap | 10807786 | 10948800 | 10694955 | 253845 | (35343) | 401914 |
| 2 | Dollar | Cross currency swap | 2000000 | 10079057 | 10666166 | (587109) | (517113) | (347294) |
| 3 | Dollar | Non-Deliverable Forward | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;150000 |  |  | (6973) | (86261) |  |
| 4 | Yen | Cross currency swap | 30000000 | 930240 | 1048553 | (118313) | (120029) | 19870 |
| **Total** |  |  |  | **21958097** | **22409674** | **(458550)** | **(758746)** | **74490** |

---

**20** **Taxes and Contributions**

**(a)** **Current and non-current assets**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Income and social contribution taxes | 606528 | 606528 | 911320 | 606528 |
| Withholding income tax (IRRF) on financial investments | 239372 | 127965 | 239952 | 128038 |
| Pis and Cofins Recoverable | 561137 | 558209 | 627155 | 558209 |
| Other federal taxes | 29071 | 2535 | 29585 | 2535 |
| **Total** | **1436108** | **1295237** | **1808012** | **1295310** |
|  **Current**<br> **Non** | **1436108** | **1295237** | **1540437** | **1295310** |
| **Non-current** | **-** | **-** | **267575** | **-** |

---

**(b)** **Current liabilities**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Income and social contribution taxes | 45061 |  | 47674 | 1312 |
| PIS and Cofins | 141758 | 144484 | 145197 | 144623 |
| INSS (social security contribution) | 34740 | 73823 | 34786 | 73865 |
| IRRF (withholding income tax) | 6326 | 327552 | 6326 | 327552 |
| Other | 64354 | 68219 | 69102 | 68240 |
| **Total** | **292239** | **614078** | **303085** | **615592** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**21** **Deferred PIS/Cofins taxes** 

**Non-current Liabilities**

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** |
| PIS/Cofins – Financial Asset | 1033246 | 1001566 |
| PIS/Cofins – Estimated Revenue | 81432 | 89049 |
| Other | 185624 | 190350 |
| **Total** | **1300302** | **1280965** |
| **Current Liabilities** | **81432** | **89049** |
| **Non-current Liabilities** | **1218870** | **1191916** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**22** **Deferred taxes and contributions**

**(a)** **Statement of financial position details**

---

| | | | |
|:---|:---|:---|:---|
|  | **Individual** | **Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** |
| **Deferred income tax assets** |  |  |  |
| &nbsp;&nbsp;Provisions | 665351 | 779141 | 653628 |
| &nbsp;&nbsp;Pension plan obligations – G1 | 125200 | 125200 | 125200 |
| &nbsp;&nbsp;Donations of underlying assets on concession agreements | 40088 | 40088 | 40764 |
| &nbsp;&nbsp;Allowance for doubtful accounts | 97446 | 97446 | 116431 |
| &nbsp;&nbsp;Allowance for losses on other accounts receivable | 54426 | 54426 | 54426 |
| &nbsp;&nbsp;Allowance for inventory losses | 129877 | 129877 | 121591 |
| &nbsp;&nbsp;Allowance for losses on works and projects |  |  | 10554 |
| &nbsp;&nbsp;Allowance for losses on write-off of assets | 46790 | 46790 | 46790 |
| &nbsp;&nbsp;Performance Agreements | 81639 | 81639 | 81143 |
| &nbsp;&nbsp;Present value adjustment (PVA) accounts receivable | 49096 | 49096 | 89073 |
| &nbsp;&nbsp;Derivative financial instruments in the profit/loss | 415105 | 415105 | 204190 |
| &nbsp;&nbsp;Deferred PIS/Cofins | 443548 | 443548 | 432777 |
| &nbsp;&nbsp;Actuarial gain/loss - Comprehensive Income |  | 84969 |  |
| &nbsp;&nbsp;Other | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;104122 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;104122 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;91657 |
| &nbsp;&nbsp;Off-set (\*) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2252688) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2409934) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2068224) |
| &nbsp;&nbsp;**Total deferred tax asset** | **-** | **41513** | **-** |
| **Deferred income tax liabilities** |  |  |  |
| &nbsp;&nbsp;&nbsp;&nbsp;Temporary difference in the concession of intangible asset | (287375) | (287375) | (290128) |
| &nbsp;&nbsp;Capitalization of borrowing costs | (543902) | (543902) | (526275) |
| &nbsp;&nbsp;Profit on supply to government entities | (574114) | (613428) | (573921) |
| &nbsp;&nbsp;Financial asset of the concession | (3797879) | (3797879) | (3681433) |
| &nbsp;&nbsp;Actuarial gain – G1 Plan | (91262) | (91262) | (91262) |
| &nbsp;&nbsp;Annual Generation Revenue (Receita Anual de Geração – RAG) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(10300) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- |
| &nbsp;&nbsp;Present value adjustment (PVA) investment property | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(107632) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- |
| &nbsp;&nbsp;Construction margin | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(34430) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(34430) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(35113) |
| &nbsp;&nbsp;Off-set (\*) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2252688 | 2409934 | 2068224 |
| &nbsp;&nbsp;**Total deferred tax liabilities** | **(3076274)** | **(3076274)** | **(3129908)** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(b)** **Changes**

---

| | | | |
|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025**<br>| **Net Change** | **March 31, 2026** |
| **Deferred income tax assets** |  |  |  |
| &nbsp;&nbsp;Provisions | 653628 | 11723 | 665351 |
| &nbsp;&nbsp;Pension plan obligations – G1 | 125200 |  | 125200 |
| &nbsp;&nbsp;Donations of underlying assets on concession agreements | 40764 | (676) | 40088 |
| &nbsp;&nbsp;Allowance for doubtful accounts | 116431 | (18985) | 97446 |
| &nbsp;&nbsp;Allowance for losses on other accounts receivable | 54426 |  | 54426 |
| &nbsp;&nbsp;Allowance for inventory losses | 121591 | 8286 | 129877 |
| &nbsp;&nbsp;Allowance for losses on works and projects | 10554 | (10554) |  |
| &nbsp;&nbsp;Allowance for losses on write-off of assets | 46790 |  | 46790 |
| &nbsp;&nbsp;Performance Agreements | 81143 | 496 | 81639 |
| &nbsp;&nbsp;Present value adjustment (PVA) accounts receivable | 89073 | (39977) | 49096 |
| &nbsp;&nbsp;Derivative financial instruments in the profit/loss | 204190 | 210915 | 415105 |
| &nbsp;&nbsp;Deferred PIS/Cofins | 432777 | 10771 | 443548 |
| &nbsp;&nbsp;Other | 91657 | 12465 | 104122 |
| &nbsp;&nbsp;Off-set (\*) | (2068224) | (184464) | (2252688) |
| **Total deferred tax asset** | **-** | **-** | **-** |
| **Deferred income tax liabilities** |  |  |  |
| &nbsp;&nbsp;Temporary difference in the concession of intangible asset | (290128) | 2753 | (287375) |
| &nbsp;&nbsp;Capitalization of borrowing costs | (526275) | (17627) | (543902) |
| &nbsp;&nbsp;Profit on supply to government entities | (573921) | (193) | (574114) |
| &nbsp;&nbsp;Financial asset of the concession | (3681433) | (116446) | (3797879) |
| &nbsp;&nbsp;Actuarial gain – G1 Plan | (91262) |  | (91262) |
| &nbsp;&nbsp;Construction margin | (35113) | 683 | (34430) |
| &nbsp;&nbsp;Off-set (\*) | 2068224 | 184464 | 2252688 |
| **Total deferred tax liabilities** | **(3129908)** | **53634** | **(3076274)** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | |
|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025**<br>| **Net Change** | **March 31, 2026** |
| **Deferred income tax assets** |  |  |  |
| &nbsp;&nbsp;Provisions | 653628 | 125513 | 779141 |
| &nbsp;&nbsp;Pension plan obligations – G1 | 125200 |  | 125200 |
| &nbsp;&nbsp;Donations of underlying assets on concession agreements | 40764 | (676) | 40088 |
| &nbsp;&nbsp;Allowance for doubtful accounts | 116431 | (18985) | 97446 |
| &nbsp;&nbsp;Allowance for losses on other accounts receivable | 54426 |  | 54426 |
| &nbsp;&nbsp;Allowance for inventory losses | 121591 | 8286 | 129877 |
| &nbsp;&nbsp;Allowance for losses on works and projects | 10554 | (10554) |  |
| &nbsp;&nbsp;Allowance for losses on write-off of assets | 46790 |  | 46790 |
| &nbsp;&nbsp;Performance Agreements | 81143 | 496 | 81639 |
| &nbsp;&nbsp;Present value adjustment (PVA) accounts receivable | 89073 | (39977) | 49096 |
| &nbsp;&nbsp;Derivative financial instruments in the profit/loss | 204190 | 210915 | 415105 |
| &nbsp;&nbsp;Deferred PIS/Cofins | 432777 | 10771 | 443548 |
| &nbsp;&nbsp;Actuarial gain/loss – Comprehensive Income |  | 84969 | 84969 |
| &nbsp;&nbsp;Other | 91657 | 12465 | 104122 |
| &nbsp;&nbsp;Off-set (\*) | (2068224) | (341710) | (2409934) |
| **Total deferred tax asset** | **-** | **41513** | **41513** |
| **Deferred income tax liabilities** |  |  |  |
| &nbsp;&nbsp;Temporary difference in the concession of intangible asset | (290128) | 2753 | (287375) |
| &nbsp;&nbsp;Capitalization of borrowing costs | (526275) | (17627) | (543902) |
| &nbsp;&nbsp;Profit on supply to government entities | (573921) | (39507) | (613428) |
| &nbsp;&nbsp;Financial asset of the concession | (3681433) | (116446) | (3797879) |
| &nbsp;&nbsp;Actuarial gain – G1 Plan | (91262) |  | (91262) |
| &nbsp;&nbsp;Construction margin | (35133) | 683 | (34430) |
| &nbsp;&nbsp;Annual Generation Revenue (Receita Anual de Geração – RAG) |  | (10300) | (10300) |
| &nbsp;&nbsp;Present value adjustment (PVA) investment property |  | (107632) | (107632) |
| &nbsp;&nbsp;Off-set (\*) | 2068224 | 341710 | 2409934 |
| **Total deferred tax liabilities** | **(3129908)** | **53634** | **(3076274)** |

---

(\*) Refers to the assets and liabilities offset in the determination of deferred tax. Historically, SABESP has recognized deferred tax liabilities, however, following the acquisition of EMAE and, consequently, the consolidation of its deferred tax asset, the Company presents the movements and offsets applied in order to reconcile deferred tax assets and deferred tax liabilities on an individual basis.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**(c)** **Reconciliation of the effective tax rate**

The amounts recorded as income tax and social contribution expenses in the quarterly information are reconciled to the statutory rates, as shown below:

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| Profit before taxes | &nbsp;&nbsp;&nbsp;&nbsp;2356132 | &nbsp;&nbsp;&nbsp;&nbsp;2249685 | &nbsp;&nbsp;&nbsp;&nbsp;2357565 | 2250926 |
| Statutory rate | 34% | 34% | 34% | 34% |
| Estimated expense at statutory rate | &nbsp;&nbsp;&nbsp;&nbsp;(801085) | &nbsp;&nbsp;&nbsp;&nbsp;(764893) | &nbsp;&nbsp;&nbsp;&nbsp;(801572) | &nbsp;&nbsp;&nbsp;&nbsp;(765315) |
| **Permanent differences** |  |  |  |  |
| Tax benefit from interest on equity | &nbsp;&nbsp;&nbsp;&nbsp;198411 | &nbsp;&nbsp;&nbsp;&nbsp;— | &nbsp;&nbsp;&nbsp;&nbsp;198411 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;— |
| &nbsp;&nbsp;Provision Law No. 4.819/1958 – G0 (i) | &nbsp;&nbsp;&nbsp;&nbsp;(13071) | &nbsp;&nbsp;&nbsp;&nbsp;(12134) | &nbsp;&nbsp;&nbsp;&nbsp;(13071) | &nbsp;&nbsp;&nbsp;&nbsp;(12134) |
| &nbsp;&nbsp;Donations | &nbsp;&nbsp;&nbsp;&nbsp;— | &nbsp;&nbsp;&nbsp;&nbsp;(100) | &nbsp;&nbsp;&nbsp;&nbsp;— | &nbsp;&nbsp;&nbsp;&nbsp;(100) |
| &nbsp;&nbsp;Tax Incentives | &nbsp;&nbsp;&nbsp;&nbsp;4512 | &nbsp;&nbsp;&nbsp;&nbsp;— | &nbsp;&nbsp;&nbsp;&nbsp;4512 | &nbsp;&nbsp;&nbsp;&nbsp;— |
| &nbsp;&nbsp;Other differences | &nbsp;&nbsp;&nbsp;&nbsp;4132 | &nbsp;&nbsp;&nbsp;&nbsp;9534 | &nbsp;&nbsp;&nbsp;&nbsp;3186 | &nbsp;&nbsp;&nbsp;&nbsp;8715 |
| Income and social contribution taxes | &nbsp;&nbsp;&nbsp;&nbsp;(607101) | &nbsp;&nbsp;&nbsp;&nbsp;(767593) | &nbsp;&nbsp;&nbsp;&nbsp;(608534) | &nbsp;&nbsp;&nbsp;&nbsp;(768834) |
| Current income and social contribution taxes; | &nbsp;&nbsp;&nbsp;&nbsp;(660735) | &nbsp;&nbsp;&nbsp;&nbsp;(694920) | &nbsp;&nbsp;&nbsp;&nbsp;(662168) | &nbsp;&nbsp;&nbsp;&nbsp;(696161) |
| Deferred income and social contribution taxes | &nbsp;&nbsp;&nbsp;&nbsp;53634 | &nbsp;&nbsp;&nbsp;&nbsp;(72673) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;53634 | &nbsp;&nbsp;&nbsp;&nbsp;(72673) |
| **Effective rate** | 26% | 34% | 26% | 34% |

---

**23** **Provisions**

**(a)** **Lawsuits and proceedings that resulted in provisions**

**(I)** **Statement of financial position details**

The Company is a party to several legal claims and administrative proceedings arising from the normal course of business, including civil, tax, labor, and environmental matters. The payment terms and amounts are defined based on the outcome of these lawsuits.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Consolidated** | **Consolidated** | **Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **December 31, 2025** | **December 31, 2025** | **December 31, 2025** |
|  | **Provisions** | **Escrow deposits** | **Provisions net of deposits** | **Provisions** | **Escrow deposits** | **Provisions net of deposits** | **Provisions** | **Escrow deposits** | **Provisions net of deposits** |
| Customer claims (i) | 127075 | (1532) | 125543 | 127075 | (1532) | 125543 | 134411 | (1510) | 132901 |
| Supplier claims (ii) | 41014 |  | 41014 | 41014 |  | 41014 | 51342 | (60) | 51282 |
| Other civil claims (iii) | 187794 | (446) | 187348 | 189879 | (446) | 189433 | 154148 | (437) | 153711 |
| Tax claims (iv) | 12107 | (451) | 11656 | 139839 | (451) | 139388 | 12236 | (646) | 11590 |
| Labor claims (v) | 1412915 | (15100) | 1397815 | 1454630 | (15100) | 1439530 | 1409720 | (16318) | 1393402 |
| Environmental claims (vi) | 154988 | (41) | 154947 | 157522 | (41) | 157481 | 160575 | (49) | 160526 |
| **Total** | **1935893** | **(17570)** | **1918323** | **2109959** | **(17570)** | **2092389** | **1922432** | **(19020)** | **1903412** |
| **Current** | **1380446** | **—** | **1380446** | **1380446** | **—** | **1380446** | **1370013** | **—** | **1370013** |
| **Non-current** | **555447** | **(17570)** | **537877** | **729513** | **(17570)** | **711943** | **552419** | **(19020)** | **533399** |

---

**(II)** **Changes**

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **December 31, 2025** | **Additional provisions** | **Interest and inflation adjustment** | **Use of the provision** | **Amounts not used (reversal)** | **March 31, 2026** |
| Customer claims (i) | 134411 | 670 | 3054 | (105) | (10955) | 127075 |
| Supplier claims (ii) | 51342 | 3137 | 7277 | (1457) | (19285) | 41014 |
| Other civil claims (iii) | 154148 | 34967 | 13788 | (3700) | (11409) | 187794 |
| Tax claims (iv) | 12236 | 35 | 191 |  | (355) | 12107 |
| Labor claims (v) | 1409720 | 56768 | 40855 | (11409) | (83019) | 1412915 |
| Environmental claims (vi) | 160575 | 4815 | 4709 | (4) | (15107) | 154988 |
| **Sub-total** | **1922432** | **100392** | **69874** | **(16675)** | **(140130)** | **1935893** |
| Escrow deposits | (19020) | (582) | (303) | (1) | 2336 | (17570) |
| **Total** | **1903412** | **99810** | **69571** | **(16676)** | **(137794)** | **1918323** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **December 31, 2025** | **Additional provisions** | **Interest and inflation adjustment** | **Use of the provision** | **Amounts not used (reversal)** | **Business combination (Note 4)** | **March 31, 2026** |
| Customer claims (i) | 134411 | 670 | 3054 | (105) | (10955) |  | 127075 |
| Supplier claims (ii) | 51342 | 3137 | 7277 | (1457) | (19285) |  | 41014 |
| Other civil claims (iii) | 154148 | 34967 | 13788 | (3700) | (11409) | 2085 | 189879 |
| Tax claims (iv) | 12236 | 35 | 191 |  | (355) | 127732 | 139839 |
| Labor claims (v) | 1409720 | 56768 | 40855 | (11409) | (83019) | 41718 | 1454633 |
| Environmental claims (vi) | 160575 | 4815 | 4709 | (4) | (15107) | 2531 | 157519 |
| **Sub-total** | **1922432** | **100392** | **69874** | **(16675)** | **(140130)** | **174066** | **2109959** |
| Escrow deposits | (19020) | (582) | (303) | (1) | 2336 |  | (17570) |
| **Total** | **1903412** | **99810** | **69571** | **(16676)** | **(137794)** | **174066** | **2092389** |

---

**(b)** **Lawsuits deemed as contingent liabilities**

The Company is a party to lawsuits and administrative proceedings relating to environmental, tax, civil, and labor claims, which are assessed as contingent liabilities in the quarterly information, since neither are outflows expected to be required nor can the amount of the obligations cannot be reliably measured. Contingent liabilities, assessed as possible loss, net of deposits, are represented as follows:

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** |
| Customer claims (i) | 247531 | 219312 |
| Supplier claims (ii) | 739787 | 925899 |
| Other civil claims (iii) | 768684 | 812534 |
| Tax claims (iv) | 1933598 | 1711737 |
| Labor claims (v) | 967499 | 918561 |
| Environmental claims (vi) | 5239227 | 5264307 |
| Total | **9896326** | **9852350** |

---

**(c)** **Explanation of the nature of the main classes of lawsuits** 

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(i)** **Customer claims** 

Refer mainly to lawsuits from customers claiming that their tariffs should be equal to those of other consumer categories, lawsuits for reduction of sewage tariff due to system losses, consequently requiring the refund of amounts charged by the Company, and lawsuits for reduction of tariff for being eligible to the Social Welfare Entity category.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(ii)** **Supplier claims** 

Include lawsuits filed by some suppliers alleging underpayment of inflation adjustments and economic and financial imbalance of the agreements, and are in progress at various courts.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(iii)** **Other civil claims** 

Refer mainly to indemnities for property damage, pain and suffering, and loss of profits allegedly caused to third parties, such as vehicle accidents, claims, and challenges on the methodology to collect tariffs, among others, filed at various court levels.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(iv)** **Tax claims** 

Tax claims refer mainly to tax collections and fines in general challenged due to disagreements regarding notification or differences in the interpretation of legislation by the Company's Management.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(v)** **Labor claims** 

The Company is a party to several labor lawsuits, involving issues such as overtime, shift schedule, health hazard premium and hazardous duty premium, prior notice, change of function, salary equalization, service outsourcing, and others, which are at various court levels.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(vi)** **Environmental claims** 

These refer to several administrative proceedings and lawsuits filed by government entities, including Companhia Ambiental do Estado de São Paulo (CETESB) and the Public Prosecution Office of the São Paulo State, which aim at certain obligations to do and not to do, demanding fines for non-compliance and imposition of compensation for environmental damages allegedly caused by the Company.

The main litigations involving the Company include: a) discharge or release of sewage without proper treatment; b) investment in the water and sewage treatment system of the municipality, under penalty of paying a fine; c) pay compensation for environmental damages; among others.

**(d)** **Guarantee insurance** 

The Company has three agreements available for the issue of policies under several types of guarantee insurance, whose limit that can be used as insurance for escrow deposit is R$3,225 million.

The guarantee insurance for escrow deposit is used in legal claims, where instead of immediately disbursing cash, the Company uses the guarantee provided by the insurance until the end of these proceedings, limited to up the effectiveness period of five years. As of March 31, 2026, the amount of R$1,498 was available for use.

From the limit available, the insured amounts of the policies issued are deducted and the technical reserves of the insurers are also considered.

---

| | |
|:---|:---|
| **24** | **Contract liability** |

---

The contract liability represents EMAE's obligation to provide construction and infrastructure improvement services for the quota power plants in exchange for amounts already received through the GAG Improvement component of the RAG, in excess of the revenue recognized in the period for the construction and improvement performance obligation. The contract liability is recognized and measured in accordance with paragraphs 105 to 108 of CPC 47 / IFRS 15, based on the difference between the total GAG Improvement amounts received since July 1, 2018 and the cumulative construction and improvement revenue recognized over the same period using the cost-plus-margin method.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

The contract liability is settled as the Company carries out the related improvement investments and recognizes the associated revenues, being reversed directly against construction revenue in profit or loss for the period. No provision is recognized based on estimated investment plans; the contract liability strictly reflects the difference between amounts received and investments effectively incurred.

The Company classifies as current liabilities the portion expected to be settled within twelve months from the reporting date, based on the projected budgeted CAPEX for the subsequent period. The remaining balance is classified as non-current liabilities.

**25** **Labor and social obligations**

---

| | | | |
|:---|:---|:---|:---|
|  | **Individual** | **Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** |
| Salaries and payroll charges | 24967 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;28396 | 62232 |
| Provision for vacation | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;187267 | 192921 | 193878 |
| Provision for 13th salary | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;19625 | 19625 |  |
| Healthcare plan (i) | 12238 | 15825 | 106589 |
| Provision for profit sharing (ii) | 74710 | 90277 | 203784 |
| Incentivized Dismissal Program - IDP (iii) | 11050 | 11050 | 17126 |
| Voluntary Dismissal Program - VDP (iii) | 75463 | 75463 | 113338 |
| Consent Decree (TAC) | 1656 | 1656 | 2163 |
| Knowledge Retention Program (KRP) | 519 | 519 | 519 |
| **Total** | **407495** | **435732** | **699629** |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(i)** **Healthcare plan** 

Benefits granted are paid after the event, free of choice, and are sponsored by the contributions of SABESP and the employees. In the first quarter of 2026, the Company contributed 8.04%, on average, of gross payroll, totaling R$37,978 (7.75% in the first quarter of 2025, totaling R$56,587) in expenses with salaries, payroll charges, and benefits.

The agreement entered into between SABESP and AAPS (SABESP's Association of Retirees and Pensioners) regarding the financial compensation to the provider of the VIVEST health plan, for the period of 60 months during the migration of retirees, former employees, pensioners and dependents between health plans, is recorded in this line.

Until March 31, 2026, the total provision amount remains R$134,751, of which R$42,187 in this line in current liabilities, and R$92,564 in non-current liabilities under the line "Other Obligations".

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(ii)** **Provision for profit sharing ("PPS")** 

The Profit Sharing Program was implemented based on an agreement with the labor unions. Payment corresponds to up to one month's salary for each employee, based on the achievement of established goals. In addition, the short-term incentive program which will be paid as PPS to the Company's management positions, subject to the achievement of individual and collective goals. This program is provisioned monthly, according to the achievement of these targets.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(iii)** **Incentivized Dismissal Program ("IDP") and Voluntary Dismissal Program ("VDPs")** 

In June 2023, the Company implemented the IDP to reduce the number of employees in a conciliatory manner, aiming at efficiency gains, increased competitiveness and optimized costs (more details in Note 21 to the Annual Financial Statements as of December 31, 2023).

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

As of March 31, 2026, the amount of R$11,050 was recorded in current liabilities, under the line "Labor and social obligations", arising from the provision for indemnity incentives for employees who joined the program. These amounts refer to Health Plan reimbursements to be implemented for 24 consecutive and uninterrupted months, until approximately June 2026.

The VDPs were implemented to reduce the number of employees in a conciliatory manner, aiming at efficiency gains, increased competitiveness and optimized costs and was carried out in three phases:

1- 2025 VDP: applications in the period from December 23, 2024 to January 31, 2025, with 2,039 applications and contractual terminations beginning February 2025 (further details in Note 23 of the Annual Financial Statements as of December 31, 2024).

2- VDPD: applications in the period from August 6, 2025 to August 29, 2025, with 145 applications and contract terminations scheduled from August 6, 2025.

3 –VDP2: applications in the period from September 1, 2025 to September 26, 2025, with 1716 applications and contract terminations according to the schedule previously established, from September 1, 2025.

Until March 31, 2026, the amount of R$75,463 was recorded in current liabilities, under the line "Labor and social obligations", arising from the provision for indemnity incentives for employees who joined the programs.

**26** **Pension plan obligations**

The Company has Post-Employment Benefits in the following modalities: Defined Benefit (BD) – G1 Plan (ii) and G0 (i); and Defined Contribution (CD) – SABESPrev Mais (iii) and VIVEST (iv), and only the latter is open for new adhesions. See the reconciliation of expenses with such plans in item (v).

**Summary of pension plan obligations - Liabilities**

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2025** | **March 31, 2025** | **March 31, 2025** |
|  | **G1 Plan** | **G0** | **Total** | **G1 Plan** | **G0** | **Total** |
| Pension obligations in the beginning of the period | (99514) | (2040647) | (2140161) |  | (1931145) | (1931145) |
| (Expenses) recognized | (2709) | (55747) | (58456) | (7052) | (58322) | (65374) |
| Payments made | 9927 | 52527 | 62454 | 7052 | 49956 | 57008 |
| **Pension obligations in the end of the period** | **(92296)** | **(2043867)** | **(2136163)** | **—** | **(1939511)** | **(1939511)** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2025** | **March 31, 2025** | **March 31, 2025** |
|  | **G1 Plan** | **G0** | **EMAE** | **Total** | **G1 Plan** | **G0** | **Total** |
| Pension obligations in the beginning of the period | (99514) | (2040647) |  | (2140161) |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1931145) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1931145) |
| (Expenses) recognized | (2709) | (55747) |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(58456) | (7052) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(58322) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(65374) |
| Payments made | 9927 | 52527 |  | 62454 | 7052 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;49956 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;57008 |
| Business combination (Note 4) | **—** | **—** | (271781) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(271781) | **—** | **—** | **—** |
| **Pension obligations in the end of the period** | **(92296)** | **(2043867)** | **(271781)** | <br> **(2407944)**  | **—** | **(1939511)** | **(1939511)** |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(i)** **G1 Plan** 

The defined benefit plan ("G1 Plan") managed by SABESPREV receives similar contributions established in a plan of subsidy of actuarial study of SABESPREV, as follows:

&nbsp;&nbsp;&nbsp;&nbsp;• 0.99% of the portion of the salary of participation
up to 20 salaries; and

&nbsp;&nbsp;&nbsp;&nbsp;• 8.39% of the surplus, if any, of the portion
of the salary of participation over 20 salaries.

&nbsp;&nbsp;&nbsp;&nbsp;**(ii) G0** 

According to State Law No. 4819/1958, employees who started providing services before May 1974 acquired a legal right to receive supplemental pension payments under the "G0 Plan". The Company pays supplemental retirement and pension amounts on behalf of the São Paulo State and seeks reimbursements of such amounts, which are recorded in the "Balances with related parties" line, limited to the amounts considered virtually certain to be reimbursed by the São Paulo State.

&nbsp;&nbsp;&nbsp;&nbsp;**(iii) Sabesprev Mais Plan** 

The sponsor's contributions correspond to the result obtained by applying a percentage of 100% to the basic contribution made by the participant.

&nbsp;&nbsp;&nbsp;&nbsp;**(iv) VIVEST Plan** 

Managed by VIVEST, the sponsor's contributions correspond to the result obtained by applying a percentage of 100% to the basic contribution made by the participant.

&nbsp;&nbsp;&nbsp;&nbsp;**(v) PSAP/EMAE and EMAE-CD**

EMAE sponsors two supplementary pension plans providing retirement and survivor benefits for its employees, former employees, and their respective beneficiaries. The plans, referred to as PSAP/EMAE and EMAE-CD, are administered by VIVEST, a closed private pension entity. The PSAP/EMAE plan has defined benefit characteristics and has been closed to new participants since 2018. In contrast, the EMAE-CD plan, established in the same year, has defined contribution characteristics and does not expose the Company to actuarial risk.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

&nbsp;&nbsp;&nbsp;&nbsp;**(vi) Reconciliation of expenditures with pension plan obligations** 

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** |
| G1 Plan (i) | 2710 | 7052 |
| Go (ii) | 55746 | 58322 |
| SABESPrev Mais Plan (iii) | 4711 | 6291 |
| VIVEST Plan (iv) | 1242 | 505 |
| **Sub-total** | **64409** | **72170** |
| Capitalized | (2755) | (2579) |
| Reimbursement of additional retirement and pension benefits paid (G0) | (17302) | (22634) |
| Other | 868 | 4813 |
| **Pension plan obligations (Note 32)** | **45220** | **51770** |

---

**27** **Services payable**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **December 31, 2025** | **March 31, 2026** | **December 31, 2025** |
| Service providers | 703348 | 633265 | 705993 | 635144 |
| Municipal Transfers | 487194 | 448224 | 487194 | 448224 |
| FAUSP (a) | 1321218 | 1361348 | 1321218 | 1361348 |
| Other services | 86948 | 325062 | 87337 | 327700 |
| **Total** | **2598708** | **2767899** | **2601742** | **2772416** |

---

(a) For further details regarding FAUSP, see Note 30 of the 2025 Annual Financial Statements.

This line records the balances payable, mainly for services received from third parties, such as the supply of electric power, reading of hydrometers and delivery of water and sewage bills, cleaning, surveillance and security services, collection, legal counsel services, audit, marketing, and advertising and consulting services, among others.

**28** **Equity** 

**(a)** **Capital stock**

As of March 31, 2026, the Company's fully subscribed and paid-in capital, totaling R$21,379,216 was composed of registered, book-entry shares with no par value, as follows:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
| **March 31, 2026, and December 31, 2025** | **Common** | | **Preferred** | | **Total Capital** | |
|  | **Number of Shares** | **%** | **Number of Shares** | **%** | **Number of Shares** | **%** |
| State of São Paulo <sup>(1)(2)</sup> | 126888269 | 18 | 1 | 100 | 126888270 | 18 |
| Equatorial S.A. | 105736018 | 15 |  |  | 105736018 | 15 |
| Free Float | 472282519 | 67 |  |  | 472282519 | 67 |
| **Total** | **704906806** | **100** | **1** | **100** | **704906807** | **100** |

---

(1) Considers 126,684,327 common shares held by the São Paulo State Treasury Department and six common shares held by Cia. Paulista de Parcerias – CPP, a company controlled by the São Paulo State.

(2) Special class preferred share.

As of March 16, 2025, the Board of Directors approved a capital increase from R$21,210,000 to R$21,379,216 with the capitalization of part of the investment reserve in the amount of R$169,216.

In a meeting held on March 16, 2026, the Board of Directors approved the distribution of dividends in the form of interest on equity in the amount of R$583,563, corresponding to the minimum mandatory dividend to be paid on April 30, 2026.

**(b)** **Long-Term Incentive Plan - ILP**

At the Extraordinary General Meeting held on April 29, 2025, SABESP's Restricted Share and Performance Plans were approved. The granting of shares is subject to the permanence of the participants in the Company and, in the case of performance shares, in addition to the fulfillment of specific goals such as the Universalization Factor (U Factor) and the Total Shareholder Return (TSR).

The Restricted Share Plan provides its participants with 4-year vesting with the acquisition of 25% of the shares each year. Specifically for the Chief Executive Officer, vesting will be 8 years, following a staggered schedule of annual acquisition.

The Performance Share Plan has a 5-year vesting with annual acquisition conditioned on the achievement of goals for its participants. In the specific case of the Chief Executive Officer, the transfer of shares is planned to occur only at the end of the program period. If U Factor goals are achieved in 2029 (universalization), as provided for in the Concession Agreement – URAE-1, the plan provides for the possibility of accelerating the vesting in October 2030 for all participants.

The number of shares to be granted will be defined by SABESP's Board of Directors, within the aggregate global limit approved by the meeting of 1% of the share capital (on a fully diluted basis).

The Restricted Share Plan and the Performance Share Plan take into account the fair value of the Company's shares on the grant date, and are measured based on the observable market price. There are no alternatives for payment in cash, so that it will be settled by means of treasury shares.

The changes in the number of shares granted, canceled or exercised under these plans are as follows:

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | |
|:---|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
| **Changes in shares** | **Performance shares** | **Restricted shares** | **Total** |
| As of march 31, 2026 | 2066834 | 366716 | 2433550 |

---

No shares were granted, exercised or canceled in the period.

As of March 31, 2026, share-based payment plans have the following maturity dates, fair value and existing shares:

**Performance shares:**

---

| | | | | |
|:---|:---|:---|:---|:---|
| **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
| **Grant date** | **Vesting rights conditions** | **Fair value on the grant date** | **Existing shares** | **Maximum remaining life** <br>|
| April 29, 2025 | Performance conditions met, 1 to 5 years of service | 92.18 | 1190252 | 5 |
| December 19, 2025 | Performance conditions met, 1 to 5 years of service | 129.87 | 876582 | 5 |

---

**Restricted shares:**

---

| | | | | |
|:---|:---|:---|:---|:---|
| **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** | **Individual and Consolidated** |
| **Grant date** | **Vesting rights conditions** | **Fair value on the grant date** | **Existing shares** | **Maximum remaining life** <br>|
| April 29, 2025 | 1 to 8 years of service | 92.18 | 253474 | 8 |
| December 19, 2025 | 1 to 4 years of service | 129.87 | 113242 | 4 |

---

As of March 31, 2026, an expense of R$36 million was recognized in profit or loss for the period referring to the Long-Term Incentive Plans, with a contra entry in Equity.

**29** **Earnings per share**

**Basic and diluted**

The following table presents the income data and number of shares used in the calculation of basic and diluted earnings per share.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | |
|:---|:---|:---|
|  | **Individual and Consolidated** | **Individual and Consolidated** |
|  | **January to March 2026** | **January to March 2025** |
|  | **January to March 2026** | **January to March 2025** |
| Profit attributable to the Company's shareholders | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1749031 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1482092 |
| Weighted average number of common shares issued for basic earnings per share (\*) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3523385573 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3417549345 |
| **Basic earnings per share (reais per share)** | **050** | **043** |
| Dilutive effect arising from: |  |  |
| Share-based payment | 475385 |  |
| Weighted average number of common shares issued adjusted for the dilutive effect | 3523860958 | 3417549345 |
| **Diluted earnings per share (reais per share)** | **050** | **043** |

---

**(\*) Share Split**

On March 27, 2026, the Company approved the submission to the shareholders, approved at the Extraordinary General Meeting to be held on April 28, 2026, of a proposal to split all common shares issued by the Company, at a ratio of 1:5, so that each 1 common share will represent 5 common shares, without changing the amount of the Company's capital ("Share Split").

The Share Split will not result in any change in the proportional interest of the shareholders in the Company's capital. The resulting shares will grant the same rights as the common shares currently outstanding, including with regard to the distribution of dividends and/or interest on equity, as well as other distributions that may be made by the Company.

As a result of the Share Split, the weighted average number of shares used in the calculation of basic and diluted earnings per share was retrospectively adjusted for all periods presented, as required by IAS 33.

**30** **Operating segment information** 

The Company's Management, composed of the Board of Directors and the Executive Board, has determined the operating segment used to make strategic decisions, such as sanitation services.

Since January 2026, following the acquisition of Empresa Metropolitana de Águas e Energia ("EMAE"), the Company has also begun operating in the planning, construction, operation, and maintenance of power generation systems, as well as in the commercialization of electric power. Due to the impracticability of determining the revenue for the period between the acquisition date and the reporting date of these financial information, only the revenue of the sanitation segment is presented below.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** | **Individual** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2025** | **March 31, 2025** | **March 31, 2025** |
|  | **Sanitation (i)** | **Reconciliation to statement of<br> profit or loss** | **Balance according to quarterly information** | **Sanitation (i)** | **Reconciliation to statement of<br> profit or loss** | **Balance according to quarterly information** |
| **Gross operating revenue** | **6.739.003** | **3.632.709** | **10.371.712** | **6.329.839** | **2.587.970** | **8.917.809** |
| Gross sales deductions | (417.152) |  | (417.152) | (501.788) |  | (501.788) |
| **Net operating revenue** | **6.321.851** | **3.632.709** | **9.954.560** | **5.828.051** | **2.587.970** | **8.416.021** |
| Selling, general and administrative expenses | (2.931.028) | (3.632.709) | (6.563.737) | (3.014.609) | (2.587.970) | (5.602.579) |
| **Operating income before other operating expenses, net and equity accounting** | **3.390.824** | **—** | **3.390.824** | **2.813.442** | **—** | **2.813.442** |
| Other operating income (expenses), net |  |  | (19.800) |  |  | 18.123 |
| Equity accounting |  |  | 12.112 |  |  | 12.567 |
| Financial income, net |  |  | (1.027.004) |  |  | (594.447) |
| Profit before income and social contribution taxes |  |  | 2.356.132 |  |  | 2.249.685 |
| Depreciation and amortization | (696.237) |  | (696.237) | (582.326) |  | (582.326) |

---

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
|  | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** | **Consolidated** |
|  | **March 31, 2026** | **March 31, 2026** | **March 31, 2026** | **March 31, 2025** | **March 31, 2025** | **March 31, 2025** |
|  | **Sanitation (i)** | **Reconciliation to statement of<br> profit or loss** | **Balance according to quarterly information** | **Sanitation (i)** | **Reconciliation to statement of<br> profit or loss** | **Balance according to quarterly information** |
| **Gross operating revenue** | **6749091** | **3633311** | **10382402** | **6339411** | **2588996** | **8928407** |
| Gross sales deductions | (417560) |  | (417560) | (502207) |  | (502207) |
| **Net operating revenue** | **6331531** | **3633311** | **9964842** | **5837204** | **2588996** | **8426200** |
| Selling, general and administrative expenses | (2937348) | (3633313) | (6570661) | (3022780) | (2588996) | (5611776) |
| **Operating income before other operating expenses, net and equity accounting** | **3394183** | **(2)** | **3394181** | **2814424** | **—** | **2814424** |
| Other operating income (expenses), net |  |  | (18827) |  |  | 18124 |
| Equity accounting |  |  | 8311 |  |  | 11348 |
| Financial income, net |  |  | (1026100) |  |  | (592970) |
| Profit before income and social contribution taxes |  |  | 2357565 |  |  | 2250926 |
| Depreciation and amortization | (697472) |  | (697472) | (583560) |  | (583560) |

---

(i) See Note 36 for further information on non-monetary items, except for depreciation and amortization, that affect segment results, as well as additional information on long-term assets.

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**31** **Operating revenue**

**Conciliation of gross operating revenue to net operating revenue:**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| Revenue from sanitation services (i) | 6356385 | 6110108 | 6366473 | 6119680 |
| Construction revenue | 3632709 | 2587970 | 3633311 | 2588996 |
| Water/sewage reducer (FAUSP) (a) | 40130 | (200498) | 40130 | (200498) |
| Financial asset of the concession (ii) | 342488 | 420229 | 342488 | 420229 |
| Sale taxes | (395785) | (473550) | (396175) | (473937) |
| Regulation, Control and Oversight Fee (TRCF) (iii) | (21367) | (28238) | (21385) | (28270) |
| **Net operating revenue** | **9954560** | **8416021** | **9964842** | **8426200** |

---

(i) Include R$44,459 referring to the TRCF charged from customers from January to March 2026 (R$30,515 from January to March 2025), in the municipalities regulated by ARSESP.

(ii) See Note 15.

(iii) Amount referring to regulatory, control, and oversight activities paid to regulatory authorities.

(a) See information in Note 30 (a) of the 2025 Annual Financial Statements.

**32** **Operating costs and expenses** 

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| **Operational costs** |  |  |  |  |
| Salaries, payroll charges, and benefits | (318937) | (441881) | (319031) | (442003) |
| Pension plan obligations | (5228) | (11237) | (5228) | (11237) |
| Construction costs (Note 30) | (3632709) | (2587970) | (3633311) | (2588996) |
| General supplies | (120067) | (68783) | (120387) | (69271) |
| Treatment supplies | (162779) | (157892) | (162889) | (158236) |
| Outsourced services | (543460) | (467598) | (544905) | (469394) |
| Electricity | (380858) | (433951) | (381544) | (439572) |
| General expenses | (232621) | (199016) | (232724) | (199152) |
| Depreciation and amortization | (648061) | (526547) | (649296) | (527781) |
|  | **(6044720)** | **(4894875)** | **(6049315)** | **(4905642)** |
| **Selling expenses** |  |  |  |  |
| Salaries, payroll charges, and benefits | (32440) | (50908) | (32482) | (50955) |
| Pension plan obligations | (656) | (1955) | (656) | (1955) |
| General supplies | (1724) | (788) | (1763) | (800) |
| Outsourced services | (99051) | (104934) | (99179) | (105109) |
| Electricity | (1472) | (287) | (1472) | (287) |
| General expenses | (268) | (5093) | (345) | (5103) |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
| Depreciation and amortization | (14949) | (8088) | (14949) | (8088) |
|  | **(150560)** | **(172053)** | **(150846)** | **(172297)** |
| **Allowance for doubtful accounts (Note 10 (c))** | **(53493)** | **(136407)** | **(53602)** | **(136699)** |
| **Administrative expenses** |  |  |  |  |
| Salaries, payroll charges, and benefits | (88075) | (109663) | (88078) | (109779) |
| Pension plan obligations | (39336) | (38578) | (39336) | (38578) |
| General supplies | (126) | 552 | (126) | 553 |
| Outsourced services | (61508) | (122051) | (61548) | (121164) |
| Electricity | (32) | (342) | (1340) | (342) |
| General expenses | (55345) | (59355) | (55801) | (59509) |
| Depreciation and amortization | (33227) | (47691) | (33227) | (47691) |
| Tax expenses | (37314) | (22116) | (37442) | (20628) |
|  | **(314963)** | **(399244)** | **(316898)** | **(397138)** |
| **Operating costs and expenses** |  |  |  |  |
| Salaries, payroll charges, and benefits | (439452) | (602452) | (439591) | (602737) |
| Pension plan obligations (Note 26 (vi)) | (45220) | (51770) | (45220) | (51770) |
| Construction costs (Note 30) | (3632709) | (2587970) | (3633311) | (2588996) |
| General supplies | (121917) | (69019) | (122276) | (69518) |
| Treatment supplies | (162779) | (157892) | (162889) | (158236) |
| Outsourced services | (704019) | (694583) | (705632) | (695667) |
| Electricity | (382362) | (434580) | (384356) | (440201) |
| General expenses | (288234) | (263464) | (288870) | (263764) |
| Depreciation and amortization | (696237) | (582326) | (697472) | (583560) |
| Tax expenses | (37314) | (22116) | (37442) | (20628) |
| Allowance for doubtful accounts (Note 10 (c)) | (53493) | (136407) | (53602) | (136699) |
| **Total** | **(6563736)** | **(5602579)** | **(6570661)** | **(5611776)** |

---

---

| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

---

**33** **Financial income, net** 

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| **Financial Expenses** |  |  |  |  |
| Interest and charges on borrowings and financing - local currency | (1263959) | (596149) | (1263959) | (596206) |
| Other financial expenses | (216040) | (224605) | (215725) | (224605) |
| Other inflation adjustments | (2521) | (18793) | (2521) | (18793) |
| Interest and inflation adjustments on provisions | (29303) | (95686) | (29303) | (95686) |
| **Total financial expenses** | **(1511823)** | **(935233)** | **(1511508)** | **(935290)** |
| **Financial income** |  |  |  |  |
| Inflation adjustment - gains | 51504 | 88595 | 51506 | 88596 |
| Income on financial investments | 531200 | 201753 | 531723 | 201971 |
| Interest income | 159243 | 72202 | 159307 | 73517 |
| PIS and Cofins | (29060) | (17236) | (29060) | (17236) |
| Other | &nbsp;&nbsp;&nbsp;&nbsp;- | 1 | &nbsp;&nbsp;&nbsp;&nbsp;- | 1 |
| **Total financial income** | **712887** | **345315** | **713476** | **346849** |
| **Financial, net before exchange rate changes** | **(798936)** | **(589918)** | **(798032)** | **(588441)** |
| **Exchange rate changes** |  |  |  |  |
| Gains (Losses) on derivative financial instruments and mark-to-market | (228068) | (4520) | (228068) | (4520) |
| Other exchange rate changes | &nbsp;&nbsp;&nbsp;&nbsp;- | (9) | &nbsp;&nbsp;&nbsp;&nbsp;- | (9) |
| **Exchange rate changes, net** | **(228068)** | **(4529)** | **(228068)** | **(4529)** |
| **Net financial result** | **(1027004)** | **(594447)** | **(1026100)** | **(592970)** |

---

**34** **Other operating income (expenses), net**

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| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| Other operating income, net | 5055 | 22287 | 6025 | 22287 |
| Other operating expenses | (24855) | (4164) | (24852) | (4163) |
|  Other operating income (expenses), net<br>| **(19800)** | **18123** | **(18827)** | **18124** |

---

Other operating income includes revenue from the sale of property, plant and equipment, right to sell electricity, indemnities and reimbursement of expenses, contractual fines and guarantees, property leases, reuse water, PURA projects and services, exclusivity agreement and bank commissions,

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

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Other operating expenses usually include the derecognition of concession assets due to obsolescence, discontinued construction works, unproductive wells, projects considered economically unfeasible, losses on property, plant and equipment, estimated losses on operational assets and asset indemnification.

**35** **Commitments**

The Company has agreements to manage and maintain its activities and to build new projects aiming at achieving the objectives proposed in its target plan. The main unrecognized committed amounts as of March 31, 2026, are as follows:

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | **1 year** | **1-3 years** | **3-5 years** | **More than 5 years** | **Total** |
| Contractual obligations - Expenses | 6024158 | 4292963 | 1389117 | 3433554 | 15139792 |
| Contractual obligations - Investments | 14577604 | 10665678 | 873611 | 452179 | 26569072 |
| **Total** | **20601762** | **14958641** | **2262728** | **3885733** | **41708864** |

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**36** **Supplemental cash flow information**

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **Individual** | **Individual** | **Consolidated** | **Consolidated** |
|  | **January to March 2026** | **January to March 2025** | **January to March 2026** | **January to March 2025** |
| Total additions to property, plant and equipment (Note 16 (b)) | 33955 | 60736 | 33955 | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;60736 |
| Total additions to contract assets (Note 13) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3755847 | 2788002 | 3756449 | 2789029 |
| Total additions to intangible assets (Note 14 (b)) |  | 1245 |  | 1245 |
| Additions from prior periods that impacted the cash flows of the current period | 2165468 |  | 2167069 |  |
| Items not affecting cash (see breakdown below) | (938307) | (1301088) | (900779) | (1301088) |
| **Total additions to intangible assets and contract assets according to statement of cash flows** | **5016963** | **1548895** | **5056694** | **1549922** |
| **Investment and financing operations affecting intangible assets but not cash:** |  |  |  |  |
| &nbsp;&nbsp;Interest capitalized in the period (Note 13 (a)) | 233801 | 173738 | 233801 | 173738 |
| &nbsp;&nbsp;Contractors payable | 664595 | 1048708 | 664595 | 1048708 |
| &nbsp;&nbsp;Performance agreements | 39911 | 78642 | 2383 | 78642 |
| **Total** | **938307** | **1301088** | **900779** | **1301088** |

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| | |
|:---|:---|
| **37** | **Events after the reporting period** |

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&nbsp;&nbsp;&nbsp;&nbsp;· **Share Incorporation** 

As of April 24, 2026, SABESP and EMAE informed their shareholders and the market in general that their respective managements will assess the feasibility of the incorporation, by SABESP, of all shares issued by EMAE not already held by SABESP.

The feasibility study of the Share Incorporation will include the identification of the authorizations, conditions, and procedures required for its implementation, as well as the establishment of independent committees to negotiate the exchange ratio, in accordance with CVM Guidance Opinion No. 35, dated September 1, 2008. In this context, SABESP submitted to the CVM the unification of the Public Tender Offer for the Sale of Control with a public tender offer to increase

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo – SABESP** <br>**Notes to the Financial Statements for the**<br>**Period ended March 31, 2026**<br>**In thousands of reais, unless otherwise stated** | ![](image_001.jpg) |

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its shareholding (collectively, the "Unified Public Tender Offer"), with the purpose of acquiring up to all of the outstanding common shares of EMAE, at a price of R$61.83 per common share (subject to adjustments based on the Selic rate).

If the Share Incorporation is effectively approved by the Companies' management bodies and their shareholders, EMAE will become a wholly owned subsidiary of SABESP, and EMAE's shareholders will receive, in exchange, shares issued by SABESP, in accordance with the exchange ratio to be negotiated by the aforementioned independent committees. The proposed Share Incorporation aims to simplify and optimize the Companies' corporate structure by consolidating their shareholder bases into a single company and reducing operating costs.

&nbsp;&nbsp;&nbsp;&nbsp;· **Ordinary General Shareholder's Meeting** 

As of April 28, 2026 was held the Annual Shareholder's Meeting. The matters approved at the meeting had no impact on these financial statements.

&nbsp;&nbsp;&nbsp;&nbsp;· **Stock Split** 

On April 28, 2026, the Extraordinary General Meeting approved the split of all common shares issued by the Company at a ratio of 1:5, whereby each 1 (one) common share will now represent 5 (five) common shares, with no change to the share capital ("Stock Split").

As a result of the Share Split, the Company's share capital will now be divided into 3,524,534,025 (three billion, five hundred twenty-four million, five hundred thirty-four thousand and twenty-five) common shares, all nominative, book-entry and without par value, and 1 (one) special class preferred share held exclusively by the State of São Paulo.

The Company's shares will be traded ex-split as of April 29, 2026, based on the shareholder position as of the record date of April 28, 2026. The shares resulting from the split will be credited to the respective shareholders on April 30, 2026 and, so they will be reflected in the shareholders' positions at the opening of the market on May 4, 2026. Such shares will grant their holders the same rights attributed to previously existing common shares, including participation in dividends and/or interest on equity and other distributions that may be declared by the Company after the present date.

As a result Stock Split, the weighted average number of shares used in the calculation of basic and diluted earnings per share has been retrospectively adjusted for all periods presented, as required by IAS 33, see Note 29.

**A free translation from Portuguese into English of independent auditor's review report on quarterly information prepared in Brazilian currency in accordance with the accounting practices adopted in Brazil and the IFRS Accounting Standards**

**Independent auditor's review report on quarterly information**

To the Shareholders and Executive Board of

**Companhia de Saneamento Básico do Estado de São Paulo – SABESP**

**Introduction**

We have reviewed the accompanying individual and consolidated interim financial information contained in the Quarterly Information Form (ITR) of Companhia de Saneamento Básico do Estado de São Paulo – SABESP (the "Company") for the quarter ended March 31, 2026, which comprises the statement of financial position as of March 31, 2026 and the related statements of profit or loss, of comprehensive income, of changes in equity and of cash flows for the three-month period then ended, including the explanatory notes.

The executive board is responsible for the preparation of the individual and consolidated interim financial information in accordance with Accounting Pronouncement CPC 21 (R1) Interim Financial Reporting, and IAS 34 Interim Financial Reporting, issued by the International Accounting Standards Board (IASB), as well as for the fair presentation of this information in conformity with the rules issued by the Brazilian Securities and Exchange Commission (CVM) applicable to the preparation of the Quarterly Information Form (ITR). Our responsibility is to express a conclusion on this interim financial information based on our review.

**Scope of review**

We conducted our review in accordance with Brazilian and international standards on review engagements (NBC TR 2410 and ISRE 2410 Review of Interim Financial Information Performed by the Independent Auditor of the Entity, respectively). A review of interim financial information consists of making inquiries, primarily of persons responsible for financial and accounting matters, and applying analytical and other review procedures. A review is substantially less in scope than an audit conducted in accordance with auditing standards and consequently does not enable us to obtain assurance that we would become aware of all significant matters that might be identified in an audit. Accordingly, we do not express an audit opinion.

**Conclusion on the individual and consolidated interim financial information**

Based on our review, nothing has come to our attention that causes us to believe that the accompanying individual and consolidated interim financial information included in the quarterly information referred to above is not prepared, in all material respects, in accordance with CPC 21 (R1) and IAS 34 applicable to the preparation of Quarterly Information Form (ITR), and presented consistently with the rules issued by the Brazilian Securities and Exchange Commission (CVM).

**Other matters** 

*Review of corresponding figures*

The individual and consolidated interim financial information of the Company for the period ended March 31, 2025, were reviewed by another independent auditor, who issued a report dated May 12, 2025, without modification.

*Statements of value added*

The abovementioned quarterly information includes the individual and consolidated statement of value added (SVA) for the three-month period ended March 31, 2026, prepared under the Company management's responsibility and presented as supplementary information under IAS 34. These statements have been subject to review procedures performed together with the review of the quarterly information with the objective to conclude whether they are reconciled to the interim 342 financial information and the accounting records, as applicable, and if their format and content are in accordance with the criteria set forth by Accounting Pronouncement CPC 09 Statement of Value Added. Based on our review, nothing has come to our attention that causes us to believe that they were not prepared, in all material respects, in accordance with the criteria set forth by this standard and consistently with the overall individual and consolidated interim financial information.

São Paulo, May 07, 2026.

ERNST & YOUNG

Auditores Independentes S/S Ltda.

CRC SP-034519/O

Original report in Portuguese signed by

Uilian Dias Castro de Oliveira

Accountant CRC SP-223185/O

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Reports and Statements / Executive Officer's Statement on the Quarterly Information** | ![](image_001.jpg) |

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**Executive Officers' Statement on the Quarterly Information** 

STATEMENT

The Executive Officers of Companhia de Saneamento Básico do Estado de São Paulo - SABESP, with Corporate Taxpayers' ID (CNPJ/MF) number 43.776.517/0001-80, headquartered at Rua Costa Carvalho, nº 300, Pinheiros, São Paulo, declare that, according to paragraph 1 of article 27, item VI of CVM Resolution 80, of March 29, 2022, that:

They reviewed, discussed, and agreed with the quarterly information for the period ended March 31, 2026.

São Paulo, May 7, 2026.

Companhia de Saneamento Básico do Estado de São Paulo – SABESP

**Carlos Augusto Leone Piani** CEO

**Daniel Szlak**

Chief Financial and Investor Relations Officer

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**<br>**Reports and Statements / Executive Officer's Statement on the Report of Independent Registered Public Accounting Firm**  | ![](image_001.jpg) |

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**Executive Officers' Statement on the Report of Independent Registered Public Accounting Firm**

Firm STATEMENT

The Executive Officers of Companhia de Saneamento Básico do Estado de São Paulo – SABESP, with Corporate Taxpayers' ID (CNPJ/MF) number 43.776.517/0001-80, headquartered at Rua Costa Carvalho, nº 300, Pinheiros, São Paulo, declare that, according to paragraph 1 of article 27, item V of CVM Resolution 80, of March 29, 2022, that:

They reviewed, discussed, and agreed with the Report of Independent Registered Public Accounting Firm on the quarterly information for the period ended March 31, 2026.

São Paulo, May 7, 2026.

Companhia de Saneamento Básico do Estado de São Paulo – SABESP

**Carlos Augusto Leone Piani** 

CEO

**Daniel Szlak**

Chief Financial and Investor Relations Officer

**<u>SIGNATURE</u>**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, in the city São Paulo, Brazil. <br>

Date: May 7, 2026

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| | |
|:---|:---|
| **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**  | **Companhia de Saneamento Básico do Estado de São Paulo - SABESP**  |
| By: | /s/ Daniel Szlak  |
|  | Name: Daniel Szlak <br> Title: Chief Financial Officer and Investor Relations Officer  |

---

**FORWARD-LOOKING STATEMENTS** 

This press release may contain forward-looking statements. These statements are statements that are not historical facts, and are based on management's current view and estimates of future economic circumstances, industry conditions, company performance and financial results. The words "anticipates", "believes", "estimates", "expects", "plans" and similar expressions, as they relate to the company, are intended to identify forward-looking statements. Statements regarding the declaration or payment of dividends, the implementation of principal operating and financing strategies and capital expenditure plans, the direction of future operations and the factors or trends affecting financial condition, liquidity or results of operations are examples of forward-looking statements. Such statements reflect the current views of management and are subject to a number of risks and uncertainties. There is no guarantee that the expected events, trends or results will actually occur. The statements are based on many assumptions and factors, including general economic and market conditions, industry conditions, and operating factors. Any changes in such assumptions or factors could cause actual results to differ materially from current expectations.

------