The income amount that would prevent you from claiming him is $4300----if his income--including unemployment was more than $4300 in 2020 you cannot claim him.
When you claim an adult all you "get" is a $500 credit for other dependents. Better look carefully at his income amount and at the support test. If he is claimed as a dependent he does not qualify to get stimulus checks.
CREDIT FOR OTHER DEPENDENTS
https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...
https://ttlc.intuit.com/community/children-dependents/help/what-does-financially-support-another-per...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
