@Sballerstein
If the parent is behind in child support or is not fulfilling custodial responsibilities, that does not give the other parent a pass to claim the child in violation of the family court order. Only the family court can relieve or modify the order. The IRS relies on one measure only, where the child physically lived more than half the nights of the year. The custodial parent can always claim their dependents if the children lived in their home more than half the nights of the year. If this violates a court custody order, the other parent would have to go to court to enforce it. While the court might look less harshly on the custodial parent for ignoring the order if the non-custodial parent is not honoring their responsibilities, there is no guarantee of this. The custodial parent should not ignore the court order unless they have appropriate legal counsel.
The fact that the non-custodial parent is not following their responsibilities does not give the custodial parent any special rights or privileges with regard to the IRS.
Also, form 3949A is irrelevant in the situation and even potentially dangerous. Form 3949A is a referral of information about possible fraud to the IRS. If the noncustodial parent issues a form 8332, and also lists their child on their own tax return correctly (as someone who lives with them but is not being claimed as a dependent because of a custody agreement), then if the non-custodial parent lists the child on their tax return incorrectly, it will automatically raise a red flag with the IRS and start an investigation. No referral is needed. On the other hand, if the custodial parent does not issue form 8332 and only files the referral to get the other parent in trouble, the IRS may end up investigating both parents. As I mentioned above, if the non-custodial parent does not report form 8332 when claiming a dependent, they may be claiming excess tax benefits for the dependent. And if the custodial parent is supposed to be issuing form 8332 but does not, this could be seen by the IRS as facilitating fraud by the other parent. I would not risk the IRS attention in this way. If the custodial parent follows the court order and the proper IRS procedures and issues a signed form 8332, they have covered all of their legal bases. If the non-custodial parent does anything wrong, the IRS will automatically find out and investigate.
