STEP 14: SIGNATURE.
Returns are not processed and refunds are not issued if returns are not signed. If you and your spouse file a joint or combined return, both of you must sign the return. Include a daytime telephone number.
If a tax professional prepared your return, he/she must also sign and enter his/her telephone number and Social Security, employer identification, or personal tax identification number.
Write "deceased" on the top of the tax return.
If your spouse died and you are filing a joint or combined return, write on the deceased's signature line "Filing as a surviving spouse" and the date of death. If you have the legal authorization to file for the decedent, sign the return with your legal title or authorization. Also, attach any forms required to be filed with your Federal return, such as Federal form 1310 or a copy of the court certificate showing your appointment as a personal representative of the decedent.