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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2018-11-29</periodOfReport>

    <dateOfOriginalSubmission>2018-12-03</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001675033</issuerCik>
        <issuerName>Great Elm Capital Corp.</issuerName>
        <issuerTradingSymbol>GECC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001688208</rptOwnerCik>
            <rptOwnerName>Kuperschmid Mark</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GREAT ELM CAPITAL CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>800 SOUTH STREET, SUITE 230</rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02453</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>2018-11-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.30</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12768</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Benmark Investments LLC</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The Form 4 filed on December 3, 2018 incorrectly reported the amount of securities the reporting person acquired on November 29, 2018. As a result of this error, the total amount of securities beneficially owned by the reporting person as of November 29, 2018 was incorrectly reported. As of the date of this filing, the reporting person owns 12,768 shares of common stock in Great Elm Capital Corp.</footnote>
        <footnote id="F2">The reporting person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F3">The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.26 to $8.35, inclusive. The reporting person undertakes to provide to Great Elm Capital Corp. (&quot;GECC&quot;), any security holder of GECC, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in herein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Adam M. Kleinman, Attorney-in-Fact for Reporting Person</signatureName>
        <signatureDate>2018-12-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
