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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-03-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001429074</rptOwnerCik>
            <rptOwnerName>Mast Capital Management, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>31 ST. JAMES AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>6TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001429076</rptOwnerCik>
            <rptOwnerName>Steinberg David J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>31 ST. JAMES AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>6TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-03-28</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6400</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.2938</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1820508</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-03-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5900</value>
                    <footnoteId id="F6"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.2688</value>
                    <footnoteId id="F7"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1814608</value>
                    <footnoteId id="F8"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-04-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>102900</value>
                    <footnoteId id="F9"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.2016</value>
                    <footnoteId id="F10"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1711708</value>
                    <footnoteId id="F11"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares of Common Stock, $0.01 Par Value, of Great Elm Capital Corp., a Maryland corporation (the &quot;Common Stock&quot; and the &quot;Issuer&quot;), sold by the following Mast Accounts: (i) 6,018 shares of Common Stock sold by Mast Select Opportunities Master Fund, L.P.  and (ii) 382 shares of Common Stock sold by Mast Admiral Master Fund, L.P.</footnote>
        <footnote id="F2">The price reported in Column 4 is not a weighted average price.  These shares were sold in a single transaction at price of $8.2938 on March 28, 2019</footnote>
        <footnote id="F3">Represents shares of Common Stock held directly by the Mast Accounts, for which MAST Capital is the investment manager, including: (i) 1,712,082 shares held by Mast Select Opportunities Master Fund, L.P and (ii) 108,426 shares held by Mast Admiral Master Fund, L.P.</footnote>
        <footnote id="F4">As the investment advisor of certain private investment funds (collectively, the &quot;MAST Accounts&quot;), including those disclosed herein, MAST Capital Management, LLC (&quot;MAST Capital&quot;) may be deemed to be the beneficial owner of the shares of Common Stock held by the MAST Accounts disclosed herein.  MAST Capital also has the right to an asset-based fee relating to the MAST Accounts.  Pursuant to Rule 16a-1, MAST Capital disclaims such beneficial ownership, except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F5">Mr. Steinberg may also be deemed to beneficially own the shares of Common Stock beneficially owned (or deemed to be beneficially owned) by MAST Capital, as he is the principal of MAST Capital.  Pursuant to Rule 16a-1, Mr. Steinberg disclaims such beneficial ownership, except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F6">Represents shares of Common Stock, $0.01 Par Value, of Great Elm Capital Corp., a Maryland corporation (the &quot;Common Stock&quot; and the &quot;Issuer&quot;), sold by the following Mast Accounts: (i) 5,549 shares of Common Stock sold by Mast Select Opportunities Master Fund, L.P.  and (ii) 351 shares of Common Stock sold by Mast Admiral Master Fund, L.P.</footnote>
        <footnote id="F7">The price reported in Column 4 is not a weighted average price.  These shares were sold in a single transaction at price of $8.2688 on March 29, 2019</footnote>
        <footnote id="F8">Represents shares of Common Stock held directly by the Mast Accounts, for which MAST Capital is the investment manager, including: (i) 1,706,533 shares held by Mast Select Opportunities Master Fund, L.P and (ii) 108,075 shares held by Mast Admiral Master Fund, L.P.</footnote>
        <footnote id="F9">Represents shares of Common Stock, $0.01 Par Value, of Great Elm Capital Corp., a Maryland corporation (the &quot;Common Stock&quot; and the &quot;Issuer&quot;), sold by the following Mast Accounts: (i) 15,047 shares of Common Stock sold by Mast Select Opportunities Master Fund, L.P. and (ii) 953 shares of Common Stock sold by Mast Admiral Master Fund, L.P.</footnote>
        <footnote id="F10">The price reported in Column 4 is a weighted average price.  These shares were sold in multiple transactions at prices ranging from $8.2 to $8.2576, inclusive, on April 1, 2019</footnote>
        <footnote id="F11">Represents shares of Common Stock held directly by the Mast Accounts, for which MAST Capital is the investment manager, including: (i) 1,609,762 shares held by Mast Select Opportunities Master Fund, L.P and (ii) 101,946 shares held by Mast Admiral Master Fund, L.P.</footnote>
    </footnotes>

    <remarks>The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2), (7), and (10) to this Form 4.</remarks>

    <ownerSignature>
        <signatureName>MAST CAPITAL MANAGEMENT, LLC, By: /s/ David J. Steinberg, Name: David J. Steinberg, Title: Authorized Signatory</signatureName>
        <signatureDate>2019-04-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ David J. Steinberg</signatureName>
        <signatureDate>2019-04-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
