If you mean a corrected W-2 Form, you can enter the form in TurboTax Online by following the steps below:
- Sign into TurboTax Online
 
- Click the orange button that says "Take me to my return"
 
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Go to Federal Taxes then Wages & Income
 
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Scroll down to Wages and Salaries and click Start/Revisit
 
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Then enter the corrected W-2 information.