    <SEC-DOCUMENT>0001140361-21-009926-index.html : 20210325
    <SEC-HEADER>0001140361-21-009926.hdr.sgml : 20210325
    <ACCEPTANCE-DATETIME>20210325104935
    ACCESSION NUMBER:		0001140361-21-009926
    CONFORMED SUBMISSION TYPE:	DEFA14A
    PUBLIC DOCUMENT COUNT:		6
    FILED AS OF DATE:		20210325
    DATE AS OF CHANGE:		20210325

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			COMMUNITY BANK SYSTEM, INC.
    		CENTRAL INDEX KEY:			0000723188
    		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
    		IRS NUMBER:				161213679
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		DEFA14A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-13695
    		FILM NUMBER:		21770807

    	BUSINESS ADDRESS:
    		STREET 1:		5790 WIDEWATERS PKWY
    		CITY:			DEWITT
    		STATE:			NY
    		ZIP:			13214
    		BUSINESS PHONE:		8007242262

    	MAIL ADDRESS:
    		STREET 1:		5790 WIDEWATERS PARKWAY
    		CITY:			DEWITT
    		STATE:			NY
    		ZIP:			13214

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COMMUNITY BANK NA, a subsidiary of Community Bank System Inc
    		DATE OF NAME CHANGE:	20130729

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COMMUNITY BANK NA, a subsidiary of Community Bank System Inc.
    		DATE OF NAME CHANGE:	20130726

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COMMUNITY BANK SYSTEM INC
    		DATE OF NAME CHANGE:	19920703
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>DEFA14A
    <SEQUENCE>1
    <FILENAME>nc10018663x2_defa14a.htm
    <DESCRIPTION>DEFA14A
    <TEXT>
    Document 1 - file: nc10018663x2_defa14a.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>2
    <FILENAME>nc10018663x2_img01.jpg
    <TEXT>
    Document 2 - file: nc10018663x2_img01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>3
    <FILENAME>nc10018663x2_nc1.jpg
    <TEXT>
    Document 3 - file: nc10018663x2_nc1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>nc10018663x2_nc2.jpg
    <TEXT>
    Document 4 - file: nc10018663x2_nc2.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>nc10018663x2_nc3.jpg
    <TEXT>
    Document 5 - file: nc10018663x2_nc3.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>nc10018663x2_nc4.jpg
    <TEXT>
    Document 6 - file: nc10018663x2_nc4.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>