Sorry---once your return has been accepted by the IRS TurboTax is done. TT cannot look into it. This is between you and the the IRS.
They sent you a letter--so wait for the letter and read it carefully. Do whatever the letter tells you to do.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
