Ariz. Rev. Stat. § 25-506
A. A petition for an ex parte order for assignment may be filed by an agency based on an order for support issued by a court or an agency in a state other than this state. The petition shall include the information required by section 25-504 and the following documents:
C. If the obligor seeks to quash the assignment, the attorney general or county attorney shall immediately notify the petitioning state of the date, time and place of the hearing and of the obligee's right to attend. The only bases for the obligor to contest the withholding are that:
F. 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 person is obligated to pay child support for more than one family and the amount available for withholding is not sufficient to meet the total combined child support obligation, any monies withheld from the obligor's earnings, income, entitlements or other monies shall be allocated to each family by the employer or payor as follows: