A payment won’t be issued to someone who has died before January 1, 2020. If you filed a joint return in 2019 and your spouse died before January 1, 2020, you won’t receive a $600 payment for your deceased spouse, but you’ll still be issued up to $600 for you and $600 for any qualifying children, if all other eligibility criteria are met.
Regarding eligible individuals who died in 2020, the Recovery Rebate Credit may be claimed on line 30 of their 2020 tax return. Please refer to the instructions for the 2020 Form 1040 for more information.