For the year of death, the surviving spouse may still file a joint return if not remarried by year-end. The surviving spouse can sign the return for the deceased spouse as long as no personal representative has been appointed. Otherwise, the personal representative would have to sign the joint return.
The word "deceased," the decedent's name, and the date of death should be written across the top of the tax return. In the name-and-address section, include the names of both spouses. Also include the spouse's Social Security number, and claim both personal exemptions. On the signature line, where it reads "spouse's signature," write "filing as surviving spouse" or have the personal representative sign.
There is no need to attach a copy of the death certificate to the federal tax return. However, certain states do require a copy of the death certificate on a taxpayer's final return.