Q. Would his girlfriend’s parents be able to claim him as a dependent on their 2021 taxes if he lived there for 6 months rent-free (while he paid for his own food etc)?
A. No. An unrelated person cannot be a "Qualifying child" and would have to meet the Qualifying relative rules, which would mean (at a minimum) he would have to live with you all year.
A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:
- Closely Related OR live with the taxpayer ALL year
- His/her gross taxable income for the year must be less than $4300 (2020).
- The taxpayer must have provided more than 1/2 his support
In either case:
- He must be a US citizen or resident of the US, Canada or Mexico
- He must not file a joint return with his spouse or be claiming a dependent of his own
- He must not be the qualifying child of another taxpayer
