X0306 4 2021-03-16 0000723188 COMMUNITY BANK SYSTEM, INC. CBU 0001485738 Fesette Neil E. C/O COMMUNITY BANK SYSTEM, INC. 5790 WIDEWATERS PARKWAY DEWITT NY 13214 1 Common Stock 7157.7738 D Phantom Stock (Deferred Stock Units) 2021-03-16 4 A 0 569 0 A Common Stock 569 2680.7101 D Phantom Stock (Deferred Compensation) Common Stock 7332.9337 7332.9337 D Includes 127.113 shares acquired pursuant to the Community Bank System, Inc. Dividend Reinvestment Plan. The reporting person has received deferred stock units under the Community Bank System, Inc. 2014 Long-Term Incentive Plan. Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Bank System, Inc. common stock and will be settled in common stock at a predetermined date. Includes 17.7946 units of phantom stock acquired on January 11, 2021, as dividend equivalents under the 2014 Long-Term Incentive Compensation Program. 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. Includes 45.4586 units of phantom stock acquired on January 11, 2021, under the Deferred Compensation Plan's dividend reinvestment feature. /s/ Danielle M. Cima, pursuant to a Confirming Statement executed by Neil E. Fesette 2021-03-17