<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>22152100 - Disclosure - Subsequent Event</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>D2013Q1</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001254699</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-03-31T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="3 Months Ended" /><Label Key="Calendar" Id="1" Label="Mar. 31, 2013" /></Labels></Column><Column FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>D2012</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001254699</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2012-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2012-12-31T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="12 Months Ended" /><Label Key="Calendar" Id="1" Label="Dec. 31, 2012" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>us-gaap_SubsequentEventsAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="" UnitID=""><Id>2</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Subsequent Events [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_SubsequentEventsTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="D2013Q1" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div style="font-size:10.0pt;font-family:Times New Roman;FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman;"&gt;
&lt;div style="FONT-SIZE: 10pt; PADDING-BOTTOM: 12px;"&gt;&lt;font style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;Subsequent Events&lt;/font&gt;&lt;/div&gt;
&lt;div style="FONT-SIZE: 10pt; PADDING-BOTTOM: 12px; TEXT-ALIGN: left;"&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;On April 17, 2013, QVC completed the redemption of the remaining&lt;/font&gt; &lt;font style="FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY: Times New Roman; TEXT-DECORATION: none;"&gt;$376 million&lt;/font&gt; &lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;principal amount of its 7.125% Senior Secured Notes due 2017 using a combination of borrowings on the senior secured credit facility and cash on hand.&lt;/font&gt;&lt;/div&gt;
&lt;div style="FONT-SIZE: 10pt; PADDING-BOTTOM: 12px; TEXT-ALIGN: left;"&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;QVC declared and paid dividends to Liberty in the amount of&lt;/font&gt; &lt;font style="FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #000000; FONT-STYLE: normal; FONT-FAMILY: Times New Roman; TEXT-DECORATION: none;"&gt;$50 million&lt;/font&gt; &lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;subsequent to&lt;/font&gt; &lt;font style="FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #000000; FONT-STYLE: normal; FONT-FAMILY: Times New Roman; TEXT-DECORATION: none;"&gt;March 31, 2013 and on or prior to May 9, 2013 (the date that QVC filed its Form 10-Q for the quarter ended March 31, 2013)&lt;/font&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;.&lt;/font&gt;&lt;/div&gt;&lt;/div&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="D2012" UnitID=""><Id>2</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div style="font-size:10.0pt;font-family:Times New Roman;FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman;"&gt;
&lt;div style="FONT-SIZE: 10pt; PADDING-BOTTOM: 12px;"&gt;&lt;font style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;(18) Subsequent Event&lt;/font&gt;&lt;/div&gt;
&lt;div style="FONT-SIZE: 10pt; PADDING-BOTTOM: 12px;"&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;QVC declared and paid dividends to Liberty in the amoun&lt;/font&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;t of $183 milli&lt;/font&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;on subsequent to December 31, 2012 and on or prior to February 20, 2013 (the date that QVC filed its Form 10-K for the year ended December 31, 2012)&lt;/font&gt;&lt;font style="FONT-SIZE: 10pt; FONT-FAMILY: inherit;"&gt;.&lt;/font&gt;&lt;/div&gt;&lt;/div&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.</ElementDefenition><ElementReferences>No definition available.</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Subsequent Events</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>Subsequent Event</ReportName><MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>true</HasCustomUnits><IsEmbedReport>false</IsEmbedReport><IsMultiCurrency>false</IsMultiCurrency><ReportType>Sheet</ReportType><RoleURI>http://www.qvc.com/role/SubsequentEvent</RoleURI><NumberOfCols>2</NumberOfCols><NumberOfRows>2</NumberOfRows></InstanceReport>
