X0306 4 2018-02-05 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 2018-02-05 4 A 0 9248 41.325 A 19488 D Common Stock 2018-02-05 4 F 0 4661 41.325 D 14827 D Common Stock 2489 I ESOP Restricted Stock Units 2018-02-05 4 A 0 1800 0 A 2019-02-06 Common Stock 1800 1800 D Restricted Stock Units 2016-02-06 Common Stock 900 900 D Restricted Stock Units 2017-02-06 Common Stock 1800 1800 D Restricted Stock Units 2018-02-06 Common Stock 1700 1700 D Total direct holdings include shares held in the Dividend Reinvestment Plan, shares jointly held with spouse acquired through the Employee Stock Purchase Plan and shares acquired pursuant to Restricted Stock Awards, Restricted Stock Units and Performance Share distributions. Each restricted stock unit represents a contingent right to receive one share of Otter Tail Corporation common stock. The restricted stock units vest in four equal installments which began February 6, 2016. The restricted stock units vest in four equal annual installments which began February 6, 2017. The restricted stock units vest in four equal annual installments beginning February 6, 2018. The restricted stock units vest in four equal annual installments beginning the date shown above. Represents shares received upon the vesting of certain performance criteria in connection with a Performance Shares Award(granted in 2015). /s/ Timothy J Rogelstad by Ella Leapaldt, Attorney-in-Fact 2018-02-07