<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-05-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000739421</issuerCik>
        <issuerName>CITIZENS FINANCIAL SERVICES INC</issuerName>
        <issuerTradingSymbol>CZFS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001503523</rptOwnerCik>
            <rptOwnerName>WILSON JEFFREY L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>11 IVES STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WELLSBORO</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>16901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EXECUTIVE VICE PRESIDENT</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON CLASS</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>90</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4733.68</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <remarks>STOCK AWARDS GRANTED PURSUANT TO THE CITIZENS FINANCIAL SERVICES, INC. 2016 EQUITY INCENTIVE PLAN VEST IN THREE EQUAL ANNUAL INSTALLMENTS COMMENCING MAY 24, 2019.</remarks>

    <ownerSignature>
        <signatureName>GINA MARIE BOOR FOR JEFFREY L WILSON UNDER POWER OF ATTORNEY DATED 10/12/2010</signatureName>
        <signatureDate>2018-05-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2018-05-24
0
0000739421
CITIZENS FINANCIAL SERVICES INC
CZFS
0001503523
WILSON JEFFREY L
11 IVES STREET
WELLSBORO
PA
16901
0
1
0
0
EXECUTIVE VICE PRESIDENT
COMMON CLASS
2018-05-24
4
A
0
90
0
A
4733.68
D
STOCK AWARDS GRANTED PURSUANT TO THE CITIZENS FINANCIAL SERVICES, INC. 2016 EQUITY INCENTIVE PLAN VEST IN THREE EQUAL ANNUAL INSTALLMENTS COMMENCING MAY 24, 2019.
GINA MARIE BOOR FOR JEFFREY L WILSON UNDER POWER OF ATTORNEY DATED 10/12/2010
2018-05-25