X0306 4 2017-03-15 0000723188 COMMUNITY BANK SYSTEM, INC. CBU 0001485474 Mucenski Edward S. C/O COMMUNITY BANK SYSTEM, INC. 5790 WIDEWATERS PARKWAY DEWITT NY 13214 1 Common Stock 2335.98 D Common Stock 1526.47 I By Spouse Common Stock 7483.079 I By PMHV 401(k) Plan Phantom Stock (Deferred Stock Units) 2017-03-15 4 A 0 553 0 A Common Stock 553 2280 D Phantom Stock (Deferred Compensation) Common Stock 8761.809 8761.809 D Includes 64.12 shares acquired pursuant to the Community Bank System, Inc. Dividend Reinvestment Plan. Includes 41.9 shares acquired pursuant to the Community Bank System, Inc. Dividend Reinvestment Plan. Includes 166.1004 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. 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 54.9087 units of phantom stock acquired on January 10, 2017 under the Deferred Compensation Plan's dividend reinvestment feature. /s/ Danielle M. Cima, pursuant to a Confirming Statement executed by Edward S. Mucenski 2017-03-17