You do not "attach" documents to e-filed returns. The data is sent electronically when you e-file. If the IRS requested a copy of your W-2 or something else last year--more likely it is because the employer did not submit it to the IRS or you had some sort of discrepancy in what was entered on your return.
When you mail your return in an envelope you have to attach copies of W-2's and any 1099's that show tax withheld.
**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.**
