Unfortunately for your daughter, a divorce decree ordering one spouse to pay certain debts does not transform those debts into that spouse's separate debts if they were originally joint debts. In many U.S. states, those tax debts are community debts owed jointly by both of them. This means that the IRS has every right to collect out of your daughter's tax refund.

Your daughter is entitled to be reimbursed by her ex, though. If he continues to refuse, her best solution may be to sue the uncooperative rascal in small claims court.

Another option, albeit a more difficult one, might be for her to return to divorce court and ask the judge to modify the order in light of what happened. The judge may be willing to change the order. For example, the revised order might state that your daughter must be given certain property that was originally ordered given to her ex, in order to make up for the debt seizure.