did you file your own returns for 2021 and 2022 and did you get the proper refunds?
it would seem that for these years being the custodial parent and maintaining a separate household for more than 1/2 the year for you and your child where you paid more than 1/2 the costs you could file as head of household and claim the child credits while he would have to file as single (unless remarried). we don't know what the divorce decree said about custody. the IRS doesn't care. it says custodial parent is the one who can claim them. on the other hand, the divorce decree might specify each could claim the child in alternating years or something else. such a ruling would requirethe custodial parent to provide the other with form 8332.
violating the court decree could end up with the parties before a judge who could impose penalties on the one violating the decree.
