Taxpayer died in January 2020, Single filing status, no will, no court-appointed or certified personal representative. She had a Revocable Trust and was Trustee prior to her death. Her son and daughter had Power of Attorney which ended when she died. I prepared IRS Form 1310 for her son to claim refund due a deceased taxpayer. Software does not support a date of death without corresponding entry in personal representative, so return must be mailed not e-filed. Son will sign Form 1310. Does he sign the 2019 1040-SR tax return, too? How? Will refund be issued payable to son? How is Oklahoma refund handled? Software has no OK Form 507 and instructions on OK Form 507 say "Do not file this form with the decedent's income tax return."
If there's no appointed personal representative and there's no surviving spouse, the person in charge of the decedent's property must file and sign the return as "personal representative."