In my state it’s support. My daughter is with me majority of the time, but my ex pays child support, so they consider our financial obligation equal ( which is kind of a joke because I make more money and he pays next to nothing in child support) anyways, we alternate years claiming our daughter .
If you are filling separately and you have not discussed who’s claiming the kids..... you need to be the first to file, because if he files before you and claims them, you will get rejected and audited. Happened to me by accident one year because my idiot ex forgot which years he claimed on. It got fixed, but it was a pain.