He only needs to file state income taxes in the state where he was employed. Also, did you pay for any portion of his college in 2022? If yes, then you should include him as a depended because you likely pay a much high tax rate than he will have since he only made $12K. My daughters go to college at our (my wife's and I) alma mater which is in a different state then us and my older daughter worked for the university. But because we paid for their college, we are still allowed to claim them as dependents even though they are basically living elsewhere (out of state) for the majority of the year.
