Ariz. Rev. Stat. § 25-503
D. The obligation for current child support shall be fully met before any payments under an order of assignment may be applied to the payment of arrearages. If a party is obligated to pay support for more than one family and the amount available is not sufficient to meet the total combined current support obligation, any monies shall be allocated to each family as follows:
J. Voluntary relinquishment of physical custody of a child to the obligor from the obligee is an affirmative defense in whole or in part to a petition for enforcement of child support arrears. In determining whether the relinquishment was voluntary, the court shall consider whether there is any evidence or history of any of the following:
Q. For the purposes of this chapter, a child is emancipated: