<SEC-DOCUMENT>0000352541-18-000035.txt : 20180316
<SEC-HEADER>0000352541-18-000035.hdr.sgml : 20180316
<ACCEPTANCE-DATETIME>20180316114023
ACCESSION NUMBER:		0000352541-18-000035
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180315
FILED AS OF DATE:		20180316
DATE AS OF CHANGE:		20180316

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GALLEGOS JAMES H
		CENTRAL INDEX KEY:			0001505376

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09894
		FILM NUMBER:		18694727

	MAIL ADDRESS:	
		STREET 1:		P O BOX 14720
		CITY:			MADISON
		STATE:			WI
		ZIP:			53708

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ALLIANT ENERGY CORP
		CENTRAL INDEX KEY:			0000352541
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC & OTHER SERVICES COMBINED [4931]
		IRS NUMBER:				391380265
		STATE OF INCORPORATION:			WI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		4902 NORTH BILTMORE LANE
		STREET 2:		SUITE 1000
		CITY:			MADISON
		STATE:			WI
		ZIP:			53718-2148
		BUSINESS PHONE:		608-458-3311

	MAIL ADDRESS:	
		STREET 1:		4902 NORTH BILTMORE LANE
		STREET 2:		SUITE 1000
		CITY:			MADISON
		STATE:			WI
		ZIP:			53718-2148

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INTERSTATE ENERGY CORP
		DATE OF NAME CHANGE:	19980427

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	WPL HOLDINGS INC
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_152121479394754.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-03-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000352541</issuerCik>
        <issuerName>ALLIANT ENERGY CORP</issuerName>
        <issuerTradingSymbol>LNT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001505376</rptOwnerCik>
            <rptOwnerName>GALLEGOS JAMES H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ALLIANT ENERGY CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>PO BOX 14720</rptOwnerStreet2>
            <rptOwnerCity>MADISON</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>53708-0720</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, Gen Cnsl and Corp Sec</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-03-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>39.80</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28860.331</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1378.2964</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(k) Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The reported price is a weighted average sale price. These shares were sold in multiple transactions at prices ranging from $39.797 to $39.807. The reporting person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range.</footnote>
        <footnote id="F2">Includes adjustments for accrued dividends, pursuant to a dividend reinvestment transaction exempt from Section 16 under Rule 16a-11.</footnote>
        <footnote id="F3">Reflects 401(k) holdings as of this filing date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jake C. Blavat, Attorney-in-Fact</signatureName>
        <signatureDate>2018-03-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
