you can't stop her from claiming the children even if she is not entitled. The IRS will only act when two returns are filed claiming the same children. then the IRS will send out notices asking each for proof they are entitled to claim them. the loser gets a bill for any taxes, penalties and interest owed. Even after the court decides who gets to claim them and what years, the IRS is not bound by that decision. The IRS looks purely at the custodial parent. the one the child or children spent more than 1/2 the nights with during the year unless the custodial parent furnished the other with form 8332. there are other rules. for example, while the court may say the noncustodial parent gets to claim them in say odd number years, the custodial parent is not bound under the tax laws to observe the decision. However, what can happen is that the noncustodial parent can haul you back into court for violating the court order and then the court can find you in contempt and level penalties.
