If an executor or administrator is involved, he or she must sign the return for the decedent. When a joint return is filed, the spouse must also sign. When there is no executor or administrator, whoever is responsible for filing the return should sign the return and note that he or she is signing "on behalf of the decedent." If a joint return is filed by the surviving spouse alone, he or she should sign the return and write "filing as surviving spouse" in the space for the other spouse's signature.
If a refund is due, there's one more step. You should also complete and file with the final return a copy of Form 1310, Statement of Person Claiming Refund Due a Deceased Taxpayer. Although the IRS says you don't have to file Form 1310 if you are a surviving spouse filing a joint return, you probably should file the form anyway to head off possible delays.
