ALLIANT ENERGY CORP - (8-K) - Disclosing Other Events.

Item 8.01 Other Events.

On September 18, 2023, Interstate Power and Light Company (“IPL”), a subsidiary of Alliant Energy Corporation, entered into an Underwriting Agreement (the “Underwriting Agreement”) with BofA Securities, Inc., Mizuho Securities USA LLC, MUFG Securities Americas Inc., U.S. Bancorp Investments, Inc., and Wells Fargo Securities, LLC, as representatives of the several underwriters listed therein (the “Underwriters”), pursuant to which IPL agreed to sell, and the Underwriters agreed to purchase, subject to the terms and conditions set forth therein, $300 million aggregate principal amount of IPL’s 5.700% Senior Debentures due 2033 (the “Debentures”), in a public offering (the “Offering”). The Debentures are to be issued under an Indenture dated as of August 20, 2003, between IPL and The Bank of New York Mellon Trust Company, N.A., as successor trustee (the “Indenture”), pursuant to an Officer’s Certificate provided pursuant to the Indenture setting forth the terms of the Debentures (the “Certificate”). The Offering is expected to close, subject to standard closing conditions, on September 21, 2023.

The Debentures are registered under the Securities Act of 1933, as amended, pursuant to an automatic shelf registration statement on Form S-3 (Registration No. 333-251353-01) that IPL filed with the Securities and Exchange Commission (the “SEC”) on December 15, 2020 (the “Registration Statement”). The Registration Statement was supplemented by a Prospectus Supplement setting forth the terms of the Debentures that IPL filed with the SEC on September 19, 2023.

This Current Report on Form 8-K is being filed for the purpose of filing exhibits to the Registration Statement relating to the public offering of the Debentures, and all such exhibits are hereby incorporated into the Registration Statement by reference. The Underwriting Agreement is filed as Exhibit 1.1 and the Certificate is filed as Exhibit 4.1 to this Form 8-K.

On September 18, 2023, IPL issued a press release announcing that it had priced the Offering. The press release is filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Perkins Coie LLP, counsel to IPL, has issued an opinion to IPL, dated September 21, 2023, regarding the legality of the Debentures upon issuance thereof, and Simmons Perrine Moyer Bergman PLC, Iowa counsel to IPL, has issued an opinion to IPL, dated September 21, 2023, regarding certain legal matters relating to Iowa law. The opinions are filed as Exhibit 5.1 and Exhibit 5.2 hereto.

Item 9.01 Financial Statements and Exhibits.

 (d)Exhibits Exhibit Number Description 1.1 Underwriting Agreement, dated September 18, 2023, among 

Interstate Power and Light Company and the underwriters named therein.

 4.1 Officer’s Certificate creating the 5.700% Senior 

Debentures due 2033 of Interstate Power and Light Company.

 5.1 Opinion of Perkins Coie LLP, dated September21, 2023, with 

respect to the5.700% Senior Debentures due2033of Interstate Power and Light Company.

 5.2 Opinion of Simmons Perrine Moyer Bergman PLC, dated 

September21, 2023, with respect to the5.700% Senior Debentures due2033of Interstate Power and Light Company.

 23.1 Consent of Perkins Coie LLP (contained in Exhibit 5.1 

hereto).

 23.2 Consent of Simmons Perrine Moyer Bergman PLC (contained in 

Exhibit 5.2 hereto).

 99.1 Press Release of Interstate Power and Light Company, dated 

September18, 2023.

 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) 

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