"He worked only briefly..." If your adult son had less than $5050 of income during 2024 ---not counting any Social Security---you may be able to claim him as a qualifying relative and get the $500 credit for other dependents. If he files a tax return of his own he will have to say on his own return that he can be claimed as someone else's dependent.
If he earned at least $5050 during the time that he worked, no one can claim him as a dependent.
IRS interview to help determine who can be claimed:
https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent
Qualifying relative
When you add someone as a dependent, we'll ask a series of questions to make sure you can claim them. There may be other tax benefits you can get when you claim a dependent.
Related Information:
It depends. Are you providing OVER half of his support and did he make less than $5,050? If so and the below apply, then yes.
To claim someone as a Qualifying Relative, they must be:
If you are sending him a check, then you can also complete this form and keep it for your records. That would be enough documentation. If he is filing a return, he would need to check the box that says someone else can claim me as a dependent on their return.
Even if he does not live with you and you are able to claim him as a dependent, then you can file as Head of Household and also claim the $500 Other Dependent Credit.
If you are not providing over half of his support, then no, you cannot claim him even if you are sending him a monthly check. This would basically be considered a gift.
(Edited 2/17/2025 @ 9:38AM PST) @tmsars4142