Form W-2c: Corrected Wage and Tax Statement is simply a corrected version of your W-2.
Your W-2c will look a little different than a regular W-2; it has two columns, Previously reported and Correct information. Enter the dollar amounts from the Correct information column. Don't forget to check the Corrected W-2 box when you get to the Do any of these uncommon situations apply? screen.
If you already imported or entered your W-2 and you haven't yet filed, go back and edit your W-2 with the corrected info from your W-2c.
And if you already mailed your return, or it was accepted, you may need to amend.