Document

SD 1 a2026formsd-conflictminera.htm SD Document

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM SD

SPECIALIZED DISCLOSURE REPORT

OTTER TAIL CORPORATION

(Exact name of registrant as specified in its charter)


Minnesota (State or other jurisdiction of incorporation or organization)			0-53713 (Commission File Number)			27-0383995 (I.R.S. Employer Identification No.)

215 South Cascade Street, P.O. Box 496, Fergus Falls, MN 56538-0496

(Address of principal executive offices, including zip code)

Jennifer O. Smestad, Esq.

Senior Vice President, General Counsel and Corporate Secretary

215 South Cascade Street, Box 496

Fergus Falls, Minnesota 56538-0496

(866) 410-8780

(Name and telephone number, including area code, of the person to contact in connection with this report)

Check the appropriate box to indicate the rule pursuant to which this form is being filed, and provide the period to which the information in this form applies:


			☒			Rule 13p-1 under the Securities Exchange Act (17 CFR 240.13p-1) for the reporting period from January 1 to December 31, 2025.

Section 1.01 and 1.02 – Conflicts Minerals Disclosure

Items 1.01 and 1.02 – Conflicts Minerals Disclosure and Report Exhibit

This Form SD and the Conflict Minerals Report, filed as Exhibit 1.01 hereto, are publicly available on our website under Investors, SEC Filings, Form SD at the website www.ottertail.com as well as the SEC’s EDGAR database at www.sec.gov. The content of any website referred to in this Form SD is included for general information only and is not incorporated by reference in this Form SD.

Section 2 - Exhibits

Item 2.01 Exhibits

1.01 Conflict Minerals Report for the reporting period January 1, 202 5 to December 31, 2025 as required by Items 1.01 and 1.02 of this Form SD.

Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.


	OTTER TAIL CORPORATION


Date: May 29, 2026	By:	/s/ Jennifer O. Smestad
		Jennifer O. Smestad
		Senior Vice President, General Counsel and Corporate Secretary