INTERSTATE POWER AND LIGHT COMPANY (an Iowa corporation) 5.700% SENIOR DEBENTURES DUE 2033 UNDERWRITING AGREEMENT Dated: September 18, 2023Underwriting Agreement • September 21st, 2023 • Interstate Power & Light Co • Electric & other services combined • New York
Interstate Power and Light Company, an Iowa corporation (the “Company”), confirms its agreement with BofA Securities, Inc., Mizuho Securities USA LLC, MUFG Securities Americas Inc., U.S. Bancorp Investments, Inc. and Wells Fargo Securities, LLC, and each of the other underwriters named in Schedule A hereto (collectively, the “Underwriters,” which term shall also include any underwriter substituted as hereinafter provided in Section 10 hereof), for whom BofA Securities, Inc., Mizuho Securities USA LLC, MUFG Securities Americas Inc., U.S. Bancorp Investments, Inc. and Wells Fargo Securities, LLC are acting as representatives (in such capacity, the “Representatives”), with respect to the issue and sale by the Company and the purchase by the Underwriters, acting severally and not jointly, of the respective principal amounts set forth on Schedule A of $300,000,000 aggregate principal amount of the Company’s 5.700% Senior Debentures due 2033 (the “Securities”). The Securities will be issued
