INTERSTATE POWER AND LIGHT COMPANY (an Iowa corporation) 3.400% SENIOR DEBENTURES DUE 2025 UNDERWRITING AGREEMENT Dated: August 13, 2015Underwriting Agreement • August 18th, 2015 • Interstate Power & Light Co • Electric & other services combined • New York
Interstate Power and Light Company, an Iowa corporation (the “Company”), confirms its agreement (the “Agreement”) with Wells Fargo Securities, LLC (“Wells Fargo”), Mitsubishi UFJ Securities (USA), Inc. (“Mitsubishi”) and Mizuho Securities USA Inc. (“Mizuho”), and each of the other underwriters named on Schedule A hereto (collectively, the “Underwriters”, which term shall also include any underwriter substituted as hereinafter provided in Section 10 hereof), for whom Wells Fargo, Mitsubishi and Mizuho 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 $250,000,000 aggregate principal amount of the Company’s 3.400% Senior Debentures due 2025 (the “Securities”). The Securities will be issued pursuant to an indenture dated as of August 20, 2003 (the “Base Indenture”) between the Company
