X0306 4 2018-04-08 0001466593 Otter Tail Corp OTTR 0001605621 ROGELSTAD TIMOTHY J 215 S CASCADE ST FERGUS FALLS MN 56537-2801 1 Sr VP, Elect Plat, Pres OTP Common Stock 2018-04-08 4 F 0 138 43.70 D 15754 D Common Stock 2563 I ESOP Grant of Restricted Stock Units. On 4/8/2018, 138 shares of Common Stock were withheld by the Corporation to pay taxes due upon vesting of restricted stock units, exempt pursuant to Rule 16b-3(e). Total direct holdings include shares held in Dividend Reinvestment Plan, shares held jointly with spouse acquired through the Employee Stock Purchase Plan and shares acquired pursuant to Restricted Stock Units and Performance Share distribution. /s/ Timothy J Rogelstad by Ella Leapaldt, Attorney-in-Fact 2018-04-13