Ariz. Const. art. 9, § 25

The state, any county, city, town, municipal corporation, or other political subdivision of the state, or any district created by law with authority to impose any tax, fee, stamp requirement, or other assessment, shall not impose or increase any sales tax, transaction privilege tax, luxury tax, excise tax, use tax, or any other transaction-based tax, fee, stamp requirement or assessment on the privilege to engage in, or the gross receipts of sales or gross income derived from, any service performed in this state. This section does not repeal or nullify any tax, fee, stamp requirement, or other assessment in effect on December 31, 2017.