Was he a full time student at any point in 2024? In other words, for the spring semester in 2024? If he was not, the answer is no, you can no longer claim him.
He is not required to file a federal return based on his income, however if he had federal income tax withheld, he can file in order to receive a refund. You did not mention what state you live in, so please check the instructions on your state income tax return, because filing requirements vary. He may or may not have to file a state tax return.
Here are the rules for claiming a dependent for a child that is not a full time student and over 18:
- Do they live with you? Your relative must live with you all year as a member of your household or be on the list of “relatives who do not live with you” in Publication 501. About 30 types of relatives are on this list, including son and daughter, so you have met this test.
- Do they make less than $5,050 in 2024 ($5,200 for 2025)? Your relative can't have a gross income of more than $5,050 in 2024 and be claimed by you as a dependent. This threshold increases to $5,200 for 2025.
- Do you financially support them? You must provide more than half of your relative's total support for the year.
