<SEC-DOCUMENT>0001127602-24-010977.txt : 20240322
<SEC-HEADER>0001127602-24-010977.hdr.sgml : 20240322
<ACCEPTANCE-DATETIME>20240322154402
ACCESSION NUMBER:		0001127602-24-010977
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20240321
FILED AS OF DATE:		20240322
DATE AS OF CHANGE:		20240322

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Sullivan Michele
		CENTRAL INDEX KEY:			0002009605
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13695
		FILM NUMBER:		24775020

	MAIL ADDRESS:	
		STREET 1:		2195 ROBERT J. CONLAN BLVD., NE
		STREET 2:		APT. 311
		CITY:			PALM BAY
		STATE:			FL
		ZIP:			32905

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COMMUNITY BANK SYSTEM, INC.
		CENTRAL INDEX KEY:			0000723188
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		ORGANIZATION NAME:           	02 Finance
		IRS NUMBER:				161213679
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	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>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-03-21</periodOfReport>

    <issuer>
        <issuerCik>0000723188</issuerCik>
        <issuerName>COMMUNITY BANK SYSTEM, INC.</issuerName>
        <issuerTradingSymbol>CBU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002009605</rptOwnerCik>
            <rptOwnerName>Sullivan Michele</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O COMMUNITY BANK SYSTEM, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>5790 WIDEWATERS PARKWAY</rptOwnerStreet2>
            <rptOwnerCity>DEWITT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>13214</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Stock (Deferred Compensation)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2024-03-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>271.8573</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>45.98</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>271.8573</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>271.8573</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">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.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Danielle M. Cima, pursuant to Confirming Statement executed by Michele Sullivan</signatureName>
        <signatureDate>2024-03-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
