X0508 4 2026-02-10 0 0001466593 Otter Tail Corp OTTR 0001726153 Smestad Jennifer O. 215 SOUTH CASCADE STREET FERGUS FALLS MN 56537 0 1 0 0 VP, General Council & Corp Sec 0 Common Stock 2026-02-11 4 A 0 6000 86.43 A 22168 D Common Stock 2026-02-11 4 F 0 3031 86.43 D 19137 D Common Stock 488 I By ESOP Restricted Stock Units 2026-02-10 4 A 0 1100 0 A 2027-02-06 Common Stock 1100 1100 D Restricted Stock Units 2024-02-06 Common Stock 325 325 D Restricted Stock Units 2025-02-06 Common Stock 500 500 D Restricted Stock Units 2026-02-06 Common Stock 900 900 D Represents shares received upon the vesting of certain performance criteria in connection with a Performance Share Award (granted in 2023). These shares were withheld by the Corporation to pay taxes due upon vesting of this award, exempt pursuant to Rule 16b-3(e). Total direct holdings include shares held jointly with spouse and shares acquired through the Employee Stock Purchase Plan, the Dividend Reinvestment Plan, and shares acquired pursuant to Restricted Stock Awards and Performance Share Awards. Each restricted stock unit represents a contingent right to receive one share of Otter Tail Corporation stock. The restricted stock units vest in four equal annual installments beginning the date shown above. /s/ Jennifer O. Smestad by James A. Versteeg, Attorney-in-Fact 2026-02-12