My spouse died at the start of 2021. How do I sign my 2020 return?

Condolences on the death of your spouse. Because you were married for all of 2020, you may file as married filing jointly. If you e-file, simply follow software instructions. If you file a paper return, the IRS says to enter “deceased,” the deceased spouse’s name, and the date of death across the top of the return. Then enter your name on the spouse’s line as “filing as surviving spouse” or, if there’s a personal representative or other court-appointed person, that person should sign as such.