Per IRS Instruction 1040, page 81:
If a taxpayer died before filing a return for 2021, the taxpayer's spouse or personal representative may have to file and sign a return for that taxpayer. A personal representative can be an executor, administrator, or anyone who is in charge of the deceased taxpayer's property. If the deceased taxpayer didn't have to file a return but had tax withheld, a return must be filed to get a refund. The person who files the return must enter “Deceased,” the deceased taxpayer's name, and the date of death across the top of the return. If this information isn't provided, it may delay the processing of the return.
If you are filing a joint return as a surviving spouse, you only need to file the tax return to claim the refund. If you are a court-appointed representative, file the return and include a copy of the certificate that shows your appointment. All other filers requesting the deceased taxpayer's refund must file the return and attach Form 1310.
To enter the date of death for the taxpayer or spouse in the TaxAct® program:
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the webpage or document at the time it is accessed.