My e-filed return was accepted but 2 months later the IRS returned my 1040 saying it was not signed. They accepted my check and 1040-V. Why am I being required to sign?

[xmasbaby0]

Was it e-filed or did  you mail it in an envelope?  What did they send back to you?   If it was filed on paper and you did not sign, why argue it--just sign it and mail it back.  The IRS wants your signature. Look closely--the new "postcard size" Form 1040 is supposed to be two half pages--front and back--but when you print it out, both sides print on one page.  Do you see the black arrow pointing to the words "Sign here" in the middle of the page?

[Opus 17]

You must sign your return to attest under penalty of perjury that it is true and accurate.

It's better for you that they cashed your check, since you are paid up, the penalties for late filing and late paying will be much lower than they could have been.