Form W-2C Corrected Wage and Tax Statement is issued by an employer if they discover they made a mistake on Form W-2. In TaxAct, you enter your wage information the same way, whether you receive Form W-2 or Form W-2C. If you need help reporting the corrected W-2, go to our Form W-2 - Entering in Program FAQ.
If you receive Form W-2C after you filed your return to the IRS (and it has been accepted), then you will need to amend your return.