Ariz. Rev. Stat. § 9-500.23
In addition to the powers provided by section 9-500.20 if approved by a municipal resolution, a city or a town may provide fire and emergency medical services outside its corporate limits to a county island as provided by section 11-251.12 or 48-853. A city or town that provides fire and emergency medical services outside its corporate limits pursuant to section 11-251.12 or 48-853 and the county treasurer for the county in which the municipality is located may enter into an agreement for the county treasurer to collect municipal fire and emergency services fees from owners of record in that area of the county. The municipality and the county treasurer may provide by agreement for the payment of the county treasurer's collection expenses from these fees, and if so provided, the fees shall include an amount for compensation of the county treasurer. Any compensation received by the county treasurer pursuant to this section shall be deposited pursuant to section 11-496.
A.R.S. § 9-500.23