A 2015 tax return cannot be e-filed. It has to be printed, signed, and mailed. Only a 2016 return can be e-filed. When you mail your 2015 tax return, make sure you attach the documents that show taxes withheld such as your W-2 or 1099's. Sign it at the bottom where it says "Sign Here" and write in the date. If you are mailing a state return as well, make sure you send them in separate envelopes to the correct addressed for federal and state returns. Use a mailing service that will track them such as UP or certified mail so you will know they have been received by the IRS and/or state.