Q. What rule takes precedence? Decree on the county level or Federal IRS law?
A. Both. For the IRS, it's federal law. The IRS got tired of refereeing divorce situations and had congress change the law so they don't have to bother. But though the court order is not binding on the IRS, it is still binding on you. If you fail to comply, the IRS will side with you. The other parent's only remedy is take you back to court.
For a detailed discussion, see: https://ttlc.intuit.com/questions/3479726-my-ex-claimed-our-child-but-our-court-order-says-i-m-suppo...
