Yes, most likely, if he lives with you.
There are two types of dependents, "Qualifying Children"(QC) and Other ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test.
A child of a taxpayer can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:
- He is under age 19, or under 24 if a full time student for at least 5 months of the year, or is totally & permanently disabled
- He did not provide more than 1/2 his own support. Scholarships are excluded from the support calculation
- He lived with the parent (including temporary absences such as away at school) for more than half the year
No specific medical diagnosis constitutes disabled to tax purposes.
“The term ‘disability’ means, with respect to an individual –
(a) a physical or mental impairment that substantially limits one or more of the major life activities of such individual;
(b) a record of such impairment; or
(c) being regarded as having such an impairment.”
For the IRS, disabled means -
"an individual shall be considered to be disabled if he is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or to be of long-continued and indefinite duration. An individual shall not be considered to be disabled unless he furnishes proof of the existence thereof in such form and manner as the Secretary may require. "
I believe the substance of that paragraph is that it is your Doctor's decision.
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 (your child does not have to live with you)
- His/her gross taxable income for the year must be less than $4400 (2022).
- 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
