The best answer is to follow the IRS instructions for the Form 1040X as referenced in the answer given by Critter. The IRS instructions say to include Form 1040X, a copy of the Form 1099-R that was added to the return, and any applicable schedules.
Use the link in the answer above to read the IRS instructions for yourself.
@bukowskir
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
