# EDGAR Filing Document

**Accession Number:** 0001466593
**File Stem:** 0001466593-25-000091
**Filing Date:** 2025-6
**Character Count:** 4880
**Document Hash:** 193cf6e7a3ca87ebff54aeb384fa48fc
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001466593-25-000091.hdr.sgml**: 20250605

**ACCESSION NUMBER**: 0001466593-25-000091

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 13

**CONFORMED PERIOD OF REPORT**: 20250604

**ITEM INFORMATION**: Other Events

**FILED AS OF DATE**: 20250605

**DATE AS OF CHANGE**: 20250605

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Otter Tail Corp
- **CENTRAL INDEX KEY:** 0001466593
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRIC SERVICES [4911]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 270383995
- **STATE OF INCORPORATION:** MN
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-53713
- **FILM NUMBER:** 251025928

**BUSINESS ADDRESS:**
- **STREET 1:** 215 S CASCADE ST
- **STREET 2:** PO BOX 496
- **CITY:** FERGUS FALLS
- **STATE:** MN
- **ZIP:** 56538-0496
- **BUSINESS PHONE:** 866-410-8780

**MAIL ADDRESS:**
- **STREET 1:** 215 S CASCADE ST
- **STREET 2:** PO BOX 496
- **CITY:** FERGUS FALLS
- **STATE:** MN
- **ZIP:** 56538-0496

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Otter Tail Holding Co
- **DATE OF NAME CHANGE:** 20090618

?xml version='1.0' encoding='ASCII'? ottr-20250604

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**WASHINGTON, D.C. 20549**

**FORM 8-K**

**CURRENT REPORT**

**Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934**

**Date of report (Date of earliest event reported): June 4, 2025**

**OTTER TAIL CORPORATION**

(Exact name of registrant as specified in its charter)

---

| | | |
|:---|:---|:---|
| **Minnesota**<br>(State or other jurisdiction of incorporation or organization) | **0-53713**<br>(Commission File Number) | **27-0383995**<br>(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)

**(866) 410-8780**

(Registrant's telephone number, including area code)

**Not Applicable**

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Securities Exchange Act of 1934:

---

| | | |
|:---|:---|:---|
| **Title of each class** | **Trading Symbol(s)** | **Name of each exchange on which registered** |
| Common Shares, par value $5.00 per share | OTTR | The Nasdaq Stock Market LLC |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 or Rule 12b-2 of the Securities Exchange Act of 1934.

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

------

**Item 8.01 Other Events**

**South Dakota Rate Case**

On June 4, 2025, Otter Tail Power Company (OTP), a wholly-owned subsidiary of Otter Tail Corporation, filed a request with the South Dakota Public Utilities Commission (SDPUC) for an increase in revenue recoverable under general rates in South Dakota. In its filing, OTP requested a net increase in annual revenue of $5.7 million, or 12.5%, based on a requested rate of return on rate base of 8.29% and a requested rate of return on equity of 10.8% on an equity ratio of 53.54% of total capital. Through this proceeding, OTP has proposed changes to the mechanism of cost and investment recovery for certain items, with recovery moving from riders into base rates. OTP has proposed that the change in rates be effective upon the earlier of (i) the SDPUC's final disposition of the request or (ii) 180 days from the filing of the request pending the SDPUC's final decision, subject to potential refunds for any adjustments upon finalization.

------

**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 hereunto duly authorized.

---

| | | |
|:---|:---|:---|
| | OTTER TAIL CORPORATION | OTTER TAIL CORPORATION |
| Date: June 5, 2025 | By: | /s/ Todd R. Wahlund |
|  |  | Todd R. Wahlund |
|  |  | Vice President and Chief Financial Officer |

---