X0306 4 2022-08-02 0 0001709682 Custom Truck One Source, Inc. CTOS 0001852519 Ross Joe P. 7701 INDEPENDENCE AVE KANSAS CITY MO 64125 0 1 0 0 President Sales Restricted Stock Unit 2022-08-02 4 A 0 200000 0 A Common Stock 200000 200000 D Performance Stock Unit 2022-08-02 4 A 0 100000 0 A Common Stock 100000 100000 D Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock. The restricted stock units vest in four equal annual installments beginning on April 1, 2024. Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the applicable performance period. ** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). By: /s/ Adam Haubenreich, Attorney-in-fact 2022-08-04