This Amendment No. 1 on Form 10-K/A (this "Amendment") amends Otter Tail Corporation's Annual Report on Form 10-K for the year ended December 31, 2025, which was originally filed with the Securities and Exchange Commission on February 18, 2026 (the "Original Filing"). Otter Tail Corporation is filing this Amendment for the sole purpose of correcting the date of the Report of Independent Registered Public Accounting Firm with respect to the audited financial statements included in the Original Filing, from February 19, 2025 to February 18, 2026. Accordingly, Item 8 of Part II of the Original Filing is being amended and restated hereby solely to reflect the corrected report date. In addition, as required by Rule 12b-15 of the Securities Exchange Act of 1934, as amended, new certifications by our principal executive officer and principal financial officer are included herein as exhibits to this Amendment. Accordingly, Item 15 of Part IV of the Original Filing is being amended and restated hereby solely to reflect the filing of these new exhibits.
This Amendment does not make any other changes to the Original Filing and does not reflect events occurring after the Original Filing or modify or update any of the information contained therein in any way other than as expressly described in this Amendment.
PCAOB ID No. 34