If you have already filed your return, first print out a copy of your original return for your records.
Then go into Turbo Tax and click Amend (change) a filed and accepted return under Manage Your Return.
It's zeroed out (which is why you need to keep a copy of your original return). You can then add any additional info that you've received, and Turbo Tax walks you through the rest!
You need to wait till your return is accepted by the IRS before you amend.
You mail the 1040X along with any schedules that changed as a result of the amendment (except the 1040).
You also include the federal copy of any new W-2s or any 1099-Rs that had tax withheld.
