The first step is to ask your employer for a corrected W-2 form. After you receive that, you'll likely want to file an amended returns (federal and state) to report the correct information.
When you're ready to amend, please follow these instructions. The form for amending a federal return is not ready yet. The information below will update when it's ready.
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
