Wondering if the back of the check they send you is supposed to say sign or if you go ahead and sign it. Because I've received a check in the mail .
If you received a check from the IRS then endorse it on the back just like you would with any other check. Cash it or deposit it in your bank account.
No matter if a check says "sign here" or not you must always endorse the back of any check you get or your bank will not accept it.