Q. Can he be independent one year and no the next?
A. Yes
That means there is no rule against doing that, if the circumstances change.
Q. Are you saying that the IRS will not allow you to become a dependent after you were an independent?
A. No. There is no such rule.
When I said "But, that also means he cannot go back to being your dependent for 2022", I assumed two circumstances do not change: 1. He still does not reside with you and 2. He still has more than $4300 of income. His support changing, alone, is not enough.
If he does not reside with you, he cannot be your qualifying child dependent. If he has more than $4300 of taxable income, he cannot be your qualifying relative dependent. Even if he has less than $4300 of income, you must provide more than half his support for him to be a qualifying relative (as oppossed to him only having to provide less than half his own support to be a qualifying child).
