X0306 4 2022-04-11 0001466593 Otter Tail Corp OTTR 0001180965 PARTAIN NATHAN I 215 S CASCADE ST FERGUS FALLS MN 56537-2801 1 Common Stock 2022-04-11 4 A 0 2000 A 7034 D Common Stock 2022-03-10 4 G 0 62561 0 A 62561 I by Trust Common Stock 1600 I by IRA Shares of Common Stock acquired under the 2014 Stock Incentive Plan, which is a grant of Restricted Stock. The shares granted on 4/11/2022 will vest in near-equal installments of one-third per year beginning April 8, 2023. This grant has a fair market value of $63.135. Total direct holdings include shares jointly held with spouse, shares held individually in the Dividend Reinvestment Plan and shares acquired individually pursuant to Restricted Stock Award distributions. These shares, previously reported under the Spousal Lifetime Access Trust were gifted to the Nathan I Partain Revocable Trust on the date shown. /s/ Nathan I Partain by Ella Leapaldt, Attorney-in-Fact 2022-04-13