According to the IRS:
“Is an incarcerated individual eligible for the payment? (updated January 14, 2021)
Yes, individuals will not be denied Economic Impact Payments solely because they are incarcerated. An incarcerated individual may be issued a payment if all eligibility requirements are met and the individual filed a 2019 tax return that was processed by the IRS. Eligible incarcerated individuals may claim a 2020 Recovery Rebate Credit on line 30 of their 2020 tax return. Please refer to the instructions for the 2020 Form 1040 for more information.”