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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-05-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001352713</issuerCik>
        <issuerName>RAM Holdings Ltd.</issuerName>
        <issuerTradingSymbol>ramr</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001335285</rptOwnerCik>
            <rptOwnerName>Tynan Steven J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5405 2 MORGAN HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SOUTH WOODSTOCK</rptOwnerCity>
            <rptOwnerState>VT</rptOwnerState>
            <rptOwnerZipCode>05071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares - par value $0.10 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2006-05-19</value>
                <footnoteId id="F1"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2470048</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Liberty Street Partners L.P.</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">1,000 common shares were acquired on 05/19/2006 and the remaining 9,000 common shares were acquired on 05/22/2006.</footnote>
        <footnote id="F2">Of the 10,000 shares purchased, 1,000 were purchased at $13.09 on 05/19/2006, 1,000 were purchased at $13.09 on 05/22/2006, 1,000 were purchased at $13.08 on 5/22/2006 and 7,000 were purchased at $13.05 on 5/22/2006.</footnote>
        <footnote id="F3">A total of 10,000 common shares were acquired by Liberty Street Partners, L.P. on May 19, 2006 through May 22, 2006.  7,000 common shares were previously acquired by Liberty Street Partners, L.P. on May 2, 2006 as previously disclosed on Form 4.  2,453,048 common shares are owned by High Ridge Capital Partners Limited Partnership as previously disclosed on Form 3.  Mr. Tynan is a Managing Member of High Ridge Capital LLC, an entity which is the general partner of HRC General Partner Limited Partnership, which entity is the general partner of High Ridge Capital Partners Limited Partnership.  Mr. Tynan disclaims beneficial ownership of any of the common shares owned by High Ridge Capital Partners Limited Partnership other than to the extent of his pecuniary interest therein, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F4">Mr. Tynan is the President of Liberty Street Corp., an entity which is the general partner of Liberty Street Partners L.P.  Mr. Tynan disclaims beneficial ownership of any of the common shares owned by Liberty Street Partners L.P. other than to the extent of his pecuniary interest therein, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Victoria W. Guest, Attorney-in-Fact</signatureName>
        <signatureDate>2006-05-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
