If he is age 19 or older and was not a full time student in 2023 and his gross income in 2023 was $4,700 or more, you will not be able to claim him as a dependent on the 2023 tax return.
If he is under the age of 24 in 2024 and is a full time student in 2024 you should be able to claim him as a dependent on your 2024 tax return under the Qualifying Child rules.
