The IRS will not tell you. But it is possible that someone used one of your SSN's by accident--maybe not even on purpose. Once a SSN is put into the system, it is impossible to e-file another return using that SSN. You did the correct thing by mailing it. The IRS will sort out the duplicate use of the SSN.
**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.**
