Ariz. Const. art. 9, § 24

The state, any county, city, town, municipality 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 any new tax, fee, stamp requirement or other assessment, direct or indirect, on the act or privilege of selling, purchasing, granting, assigning, transferring, receiving, or otherwise conveying any interest in real property. This section does not apply to any tax, fee, or other assessment in existence on December 31, 2007.