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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-05-01</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000870385</issuerCik>
        <issuerName>CAROLINA FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>CARO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001408738</rptOwnerCik>
            <rptOwnerName>Watts Claudius E. IV</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>THE CARLYLE GROUP</rptOwnerStreet1>
            <rptOwnerStreet2>101 S. TRYON STREET, 25TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28280</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-05-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>71143</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Disposed of in accordance with the Agreement and Plan of Merger, dated as of November 17, 2019 (the &quot;Merger Agreement&quot;) by and between Carolina Financial Corporation and United Bancshares, Inc., pursuant to which Carolina Financial Corporation was merged with and into United Bancshares Inc., effective May 1, 2020 (the &quot;Merger&quot;). On May 1, 2020, the effective date of the Merger, each issued and outstanding share of Carolina Financial Corporation common stock was converted into the right to receive 1.13 shares of United Bancshares, Inc. common stock (subject to the payment of cash in lieu of fractional shares). As a result of the Merger, a Reporting Person no longer beneficially owns, directly or indirectly, any shares of Carolina Financial Corporation common stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Claudius E. Watts, IV</signatureName>
        <signatureDate>2020-05-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
