# EDGAR Filing Document

**Accession Number:** 0000052485
**File Stem:** 0001193125-25-198338
**Filing Date:** 2025-9
**Character Count:** 5816
**Document Hash:** 303aebd449d0c1a118137bf547cd7491
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-198338.hdr.sgml**: 20250908

**ACCESSION NUMBER**: 0001193125-25-198338

**CONFORMED SUBMISSION TYPE**: FWP

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250908

**DATE AS OF CHANGE**: 20250908

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** INTERSTATE POWER & LIGHT CO
- **CENTRAL INDEX KEY:** 0000052485
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRIC & OTHER SERVICES COMBINED [4931]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 420331370
- **STATE OF INCORPORATION:** IA
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** FWP
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 333-276062-01
- **FILM NUMBER:** 251300127

**BUSINESS ADDRESS:**
- **STREET 1:** 200 FIRST ST SE
- **STREET 2:** ALLIANT ENERGY TOWER
- **CITY:** CEDAR RAPIDS
- **STATE:** IA
- **ZIP:** 52401
- **BUSINESS PHONE:** 3193984411

**MAIL ADDRESS:**
- **STREET 1:** 200 FIRST ST SE
- **STREET 2:** ALLIANT ENERGY TOWER
- **CITY:** CEDAR RAPIDS
- **STATE:** IA
- **ZIP:** 52401

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IES UTILITIES INC
- **DATE OF NAME CHANGE:** 20020103

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IES UTILITIES INC
- **DATE OF NAME CHANGE:** 19940107

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IOWA ELECTRIC LIGHT & POWER CO
- **DATE OF NAME CHANGE:** 19920703
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** INTERSTATE POWER & LIGHT CO
- **CENTRAL INDEX KEY:** 0000052485
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRIC & OTHER SERVICES COMBINED [4931]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 420331370
- **STATE OF INCORPORATION:** IA
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** FWP

**BUSINESS ADDRESS:**
- **STREET 1:** 200 FIRST ST SE
- **STREET 2:** ALLIANT ENERGY TOWER
- **CITY:** CEDAR RAPIDS
- **STATE:** IA
- **ZIP:** 52401
- **BUSINESS PHONE:** 3193984411

**MAIL ADDRESS:**
- **STREET 1:** 200 FIRST ST SE
- **STREET 2:** ALLIANT ENERGY TOWER
- **CITY:** CEDAR RAPIDS
- **STATE:** IA
- **ZIP:** 52401

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IES UTILITIES INC
- **DATE OF NAME CHANGE:** 20020103

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IES UTILITIES INC
- **DATE OF NAME CHANGE:** 19940107

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IOWA ELECTRIC LIGHT & POWER CO
- **DATE OF NAME CHANGE:** 19920703

**Filed Pursuant to Rule 433** 

**Dated September 8, 2025** 

**Registration Statement No. 333-276062-01** 

<u>INTERSTATE POWER AND LIGHT COMPANY</u> 

<u>Final Term Sheet</u> 

<u>Dated September 8, 2025</u> 

**<u>5.600% Senior Debentures due 2055</u>**

---

| | |
|:---|:---|
| Issuer: | Interstate Power and Light Company (the "**Company**") |
| Security Type: | Senior Debentures |
| Principal Amount: | $300000000 |
| Maturity Date: | October 1, 2055 |
| Coupon: | 5.600% |
| Price to Public: | 99.005% of the principal amount |
| Yield to Maturity: | 5.669% |
| Benchmark Treasury: | 4.750% due May 15, 2055 |
| Benchmark Treasury Yield: | 4.719% |
| Spread to Benchmark Treasury: | +95 bps |
| Interest Payment Dates: | April 1 and October 1, commencing April 1, 2026 |
| Optional Redemption – Reinvestment Rate: | Prior to April 1, 2055, make-whole call at T+15 bps |
| Optional Redemption at Par: | On or after April 1, 2055 |
| Trade Date: | September 8, 2025 |
| Settlement Date: | September 11, 2025 (T+3) |
| CUSIP: | 461070AY0 |
| ISIN: | US461070AY09 |
| Denominations / Multiples: | $2,000 x $1,000 |
| Anticipated Ratings\*: | Baa1 / BBB+ (Moody's / S&P) |
| Joint Book-Running Managers: | KeyBanc Capital Markets Inc.<br> PNC Capital Markets LLC<br> TD Securities (USA) LLC<br> U.S. Bancorp Investments, Inc. |
| Co-Managers: | Academy Securities, Inc.<br> Comerica Securities, Inc. |

---

\* A securities rating is not a recommendation to buy, sell or hold securities and may be subject to revision or withdrawal at any time.

------

**It is expected that delivery of the Senior Debentures will be made against payment therefor on or about September 11, 2025, which will be the third business day following the date of pricing of the Senior Debentures. Under Rule 15c6-1 of the Securities Exchange Act of 1934, trades in the secondary market generally are required to settle in one business day, unless the parties to any such trade expressly agree otherwise. Accordingly, by virtue of the fact that the Senior Debentures initially will settle in T+3, purchasers who wish to trade the Senior Debentures on any date prior to the business day before delivery should specify an extended settlement cycle at the time they enter into any such trade to prevent failed settlement and should consult their own advisors.** 

**The issuer has filed a registration statement (including a prospectus) with the Securities & Exchange Commission (the "SEC") for the offering to which this communication relates. Before you invest, you should read the prospectus in that registration statement and other documents that the issuer has filed with the SEC for more complete information about the issuer and this offering. You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, you may request a copy of these documents by calling KeyBanc Capital Markets Inc. toll free at 1-216-689-0976, PNC Capital Markets LLC toll free at 1-855-881-0697, TD Securities (USA) LLC toll free at 1-855-495-9846, or U.S. Bancorp Investments, Inc. toll free at 1-877-558-2607.** 

**Any disclaimers or other notices that may appear below are not applicable to this communication and should be disregarded. Such disclaimers and other notices were automatically generated as a result of this communication being sent via Bloomberg or another email system.**