-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Ufyez6A5AmAOdhKCHJIEDjTQPxC4vP+YAixTyP1A2zKCsXMtKVZGeXjXSv6DoH1/
 bFOV2zLhqhoPxQdN1yA50w==

<SEC-DOCUMENT>0000906602-04-000003.txt : 20040127
<SEC-HEADER>0000906602-04-000003.hdr.sgml : 20040127
<ACCEPTANCE-DATETIME>20040127133824
ACCESSION NUMBER:		0000906602-04-000003
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040126
FILED AS OF DATE:		20040127

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			UIL HOLDINGS CORP
		CENTRAL INDEX KEY:			0001082510
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC SERVICES [4911]
		IRS NUMBER:				061541045
		STATE OF INCORPORATION:			CT
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		157 CHURCH ST
		CITY:			NEW HAVEN
		STATE:			CT
		ZIP:			06510
		BUSINESS PHONE:		2034992000

	MAIL ADDRESS:	
		STREET 1:		157 CHURCH ST
		CITY:			NEW HAVEN
		STATE:			CT
		ZIP:			06510

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CHASE ARNOLD L
		CENTRAL INDEX KEY:			0001024134

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15052
		FILM NUMBER:		04545720

	BUSINESS ADDRESS:	
		STREET 1:		C/O CHASE ENTERPRISES
		STREET 2:		ONE COMMERCIAL PLAZA
		CITY:			HARTFORD
		STATE:			CT
		ZIP:			06103-3599
		BUSINESS PHONE:		8605491674

	MAIL ADDRESS:	
		STREET 1:		C/O CHASE ENTERPRISES
		STREET 2:		ONE COMMERCIAL PLAZA
		CITY:			HARTFORD
		STATE:			CT
		ZIP:			06103-3599
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-01-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001082510</issuerCik>
        <issuerName>UIL HOLDINGS CORP</issuerName>
        <issuerTradingSymbol>UIL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001024134</rptOwnerCik>
            <rptOwnerName>CHASE ARNOLD L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CHASE ENTERPRISES</rptOwnerStreet1>
            <rptOwnerStreet2>ONE COMMERCIAL PLAZA</rptOwnerStreet2>
            <rptOwnerCity>HARTFORD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06103-3599</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-01-26</value>
                <footnoteId id="F2"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21.34</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>46.87</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21.34</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5690.08</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">1-for-1</footnote>
        <footnote id="F2">The phantom stock units were accrued under the UIL Holdings Corp. Non-Employee Directors Common Stock and Deferred Compensation Plan (the &quot;Plan&quot;).</footnote>
        <footnote id="F3">The units are to be settled in UIL Holdings Corp. Common Stock upon termination of the Reporting Person's service (other than by death) or termination of the Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Theresa A. Kasuga (Theresa A. Kasuga as Attorney-in-Fact for Arnold L. Chase)</signatureName>
        <signatureDate>2004-01-27</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----