# EDGAR Filing Document

**Accession Number:** 0000883618
**File Stem:** 0001999371-25-017146
**Filing Date:** 2025-11
**Character Count:** 8811
**Document Hash:** 37502f19181901556c10203678997502
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001999371-25-017146.hdr.sgml**: 20251106

**ACCESSION NUMBER**: 0001999371-25-017146

**CONFORMED SUBMISSION TYPE**: 425

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20251106

**DATE AS OF CHANGE**: 20251106

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** NUVEEN CALIFORNIA SELECT TAX FREE INCOME PORTFOLIO
- **CENTRAL INDEX KEY:** 0000885732

**ORGANIZATION NAME:**
- **EIN:** 363828111
- **STATE OF INCORPORATION:** MA

**FILING VALUES:**
- **FORM TYPE:** 425
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 811-06623
- **FILM NUMBER:** 251459570

**BUSINESS ADDRESS:**
- **STREET 1:** 333 W WACKER DR
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606
- **BUSINESS PHONE:** 3129178200

**MAIL ADDRESS:**
- **STREET 1:** 333 W WACKER DRIVE
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NUVEEN INSURED CALIFORNIA SELECT TAX FREE INCOME PORTFOLIO
- **DATE OF NAME CHANGE:** 19920929

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NUVEEN CALIFORNIA SELECT TAX FREE INCOME PORTFOLIO
- **DATE OF NAME CHANGE:** 19600201
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** NUVEEN SELECT TAX FREE INCOME PORTFOLIO
- **CENTRAL INDEX KEY:** 0000883618

**ORGANIZATION NAME:**
- **EIN:** 363806843
- **FISCAL YEAR END:** 0331

**FILING VALUES:**
- **FORM TYPE:** 425

**BUSINESS ADDRESS:**
- **STREET 1:** 333 W WACKER DR
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606
- **BUSINESS PHONE:** 3129178200

**MAIL ADDRESS:**
- **STREET 1:** 333 W WACKER DR
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606

Filed by Nuveen Select Tax-Free Income Portfolio (Commission File No. 333-288619) pursuant to Rule 425 under the Securities Act of 1933, as amended, and deemed filed pursuant to Rule 14a-6 under the Securities Exchange Act of 1934, as amended<br> Subject Company: Nuveen California Select Tax-Free Income Portfolio<br> (Commission File No. 811-06623)<br>

**Nuveen California Select Tax-Free Income Portfolio (NXC)**

**Nuveen New York Select Tax-Free Income Portfolio (NXN)**

**Nuveen Select Tax-Free Income Portfolio (NXP)**

**Supplemental Material for Proxy Advisory Firm**

**November 6, 2025**

Below is additional information related to the Joint Proxy Statement/Prospectus dated August 25, 2025. Holders of common shares of Nuveen California Select Tax-Free Income Portfolio (NXC), Nuveen New York Select Tax-Free Income Portfolio (NXN), and Nuveen Select Tax-Free Income Portfolio (NXP) are being asked to vote on a reorganization proposal which would result in the transfer of all assets and liabilities of NXC and NXN to NXP in exchange for newly issued common shares of NXP.

While the reorganization will result in the loss of the state tax exemption for NXC and NXN shareholders, the Board considered several benefits of the reorganizations. Below, we provide further information about the Board's recommendation for the reorganization.

&nbsp;&nbsp;&nbsp;&nbsp;· Reorganization would significantly
increase scale for the target funds (NXC and NXN), while also adding incremental scale for the acquiring fund (NXP).

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** |
|  | **NXC** | **NXN** | **NXP** | **Merged** |
| **Assets** | 84364324 | 47538986 | 743527913 | 875431223 |
| **% of Merged Fund** | 9.6% | 5.4% | 84.9% |  |

---

&nbsp;&nbsp;&nbsp;&nbsp;· NXP's earnings yield is
higher than both NXC and NXN, and it is expected the fund will be able to maintain or improve its portfolio yield following the portfolio
transition post-reorganization.

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** |
| | **NXC** | **NXN** | **NXP** | **Merged** |
| **Earnings Yield** | 3.99% | 4.09% | 4.46% | 4.46% |
| **Change** | +0.47% | +0.37% | No Change | N/A |

---

&nbsp;&nbsp;&nbsp;&nbsp;· Total
operating expenses are expected to decline for all funds as a result of increased scale. NXP's management fee schedule has lower
fees at each breakpoint, so additional assets will result in increased savings for NXP while providing more meaningful fee savings for
both NXC and NXN shareholders. Additionally, fixed other expenses will be spread across a larger asset base, resulting in reduced other
expenses.

---

| | | | | |
|:---|:---|:---|:---|:---|
| | **Management**<br> **Fees** | **Other**<br> **Expenses** | **Total Operating Expenses** | **Operating Expense Savings** |
| **NXC** | 0.26% | 0.12% | 0.38% | 0.15% |
| **NXN** | 0.26% | 0.19% | 0.45% | 0.22% |
| **NXP** | 0.18% | 0.05% | 0.23% | 0.00% |
| **Merged** | 0.18% | 0.05% | 0.23% |  |

---

&nbsp;&nbsp;&nbsp;&nbsp;· As
a result of greater market capitalization, we anticipate NXP shareholders will experience better secondary market trading in terms of
narrower bid/ask spreads and greater liquidity. NXC and NXN shareholders through the reorganization into NXP should experience significant
bid/ask spread improvement as well as materially greater liquidity.

---

| | | | |
|:---|:---|:---|:---|
|  | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** |
| | **6 Month Avg Bid/Ask Spreads (bps)** | **Bid/Ask Spread Improvement (bps)** | **Average Daily Trading Volume** |
| **NXC** | 51.30 | +15.43 | Increase |
| **NXN** | 286.04 | +250.17 | Increase |
| **NXP** | 35.87 | Improves | Increase |

---

&nbsp;&nbsp;&nbsp;&nbsp;· Over time, all three funds have
traded relatively well in the secondary market, although NXP has consistently traded better in the secondary market. As a result of the
reorganization, common shares of the combined fund are expected to trade at a materially narrower discount relative to the historical
discounts of NXC and NXN. While there can be no guarantee that the combined fund will trade at a narrower discount, NXP's common
shares have traded at a discount that has historically been lower than that of NXC and NXN. Below is the premium/discount history for
the funds as of May 31, 2025.

---

| | | | |
|:---|:---|:---|:---|
|  | **NXC** | **NXN** | **NXP** |
| **Current** | -3.7% | -4.8% | 0.6% |
| **1-Year Average** | -3.2% | -6.8% | 1.1% |
| **3-Year Average** | -3.6% | -6.7% | -0.9% |
| **5-Year Average** | -1.7% | -6.0% | 0.3% |

---

&nbsp;&nbsp;&nbsp;&nbsp;· NXP has produced incremental
NAV and market price returns for shareholders over each time period when compared to both NXC and NXN. NXP's broader investable
universe has contributed to its outperformance when compared to the state funds.

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** |
|  | **Market Price** | **Market Price** | **Market Price** | **Market Price** | **NAV** | **NAV** | **NAV** | **NAV** |
|  | **<u>1Y</u>** | **<u>3Y</u>** | **<u>5Y</u>** | **<u>10Y</u>** | **<u>1Y</u>** | **<u>3Y</u>** | **<u>5Y</u>** | **<u>10Y</u>** |
| **NXC** | 2.25% | 0.31% | -0.03% | 1.97% | 0.54% | 1.01% | 0.12% | 2.35% |
| **NXN** | 3.80% | 2.85% | 1.22% | 2.32% | 0.56% | 1.18% | 0.52% | 1.91% |
| **NXP** | 3.88% | 3.68% | 2.22% | 4.00% | 1.64% | 2.09% | 1.20% | 3.08% |

---

&nbsp;&nbsp;&nbsp;&nbsp;· When
summarizing net benefits to shareholders, it is expected that all fund shareholders will experience fee and expense savings, in addition
to meaningful benefits from tighter bid/ask spreads and greater liquidity due to increased trading volumes.

---

| | | | |
|:---|:---|:---|:---|
|  | **As of May 31, 2025** | **As of May 31, 2025** | **As of May 31, 2025** |
| | **NXC** | **NXN** | **NXP** |
| **Operating Change Summary** | | | |
| **Earnings Yield Change** | +0.47% | +0.37% | No Change |
| **Management Fee Savings** | +0.080% | +0.080% | +0.002% |
| **Other Expense Savings** | +0.070% | +0.140% | +0.001% |
| **Loss of State Tax Exemption Earnings Impact<sup>1</sup>** | -0.13% | -0.34% | No Change |
| **Secondary Market Change Summary** | **Secondary Market Change Summary** | **Secondary Market Change Summary** | **Secondary Market Change Summary** |
| **Discount Narrowing (3-year average)** | +2.68% | +5.77% | No Change |
| **Bid/Ask Spread Improvement (bps)** | +15.43 | +250.17 | Improves |
| **Average Daily Trading Volume** | Increase | Increase | Increase |

---

<sup>1</sup> Loss of State Tax Exemption for NXC and NXN is estimated by calculating the taxable equivalent earnings rate for each fund assuming the maximum state tax rate and comparing to the net earnings rate of NXP.