X0508 4 2023-12-01 0000723188 COMMUNITY BANK SYSTEM, INC. CBU 0001485739 Whipple John F. C/O COMMUNITY BANK SYSTEM, INC. 5790 WIDEWATERS PARKWAY DEWITT NY 13214 1 0 Common Stock 2023-12-01 4 M 0 1259.403 44.36 A 5115.0302 D Phantom Stock (Deferred Compensation) 2023-12-01 4 M 0 1259.403 0 D Common Stock 1259.403 7607.2548 D On December 1, 2023, the reporting person's phantom stock units were settled for an equal number of shares of Community Bank System, Inc. common stock. Each unit of phantom stock is the economic equivalent of one share of Community Bank System, Inc. common stock. The units of phantom stock relating to the Deferred Compensation Plan will be settled in Community Bank System, Inc. common stock at future dates selected by the reporting person. /s/ Danielle M. Cima, pursuant to a Confirming Statement executed by John F. Whipple, Jr. 2023-12-05