Ariz. Rev. Stat. § 16-121 – Qualified elector; definition

A. A person who is qualified to register to vote pursuant to section 16-101 and who is properly registered to vote, if the person is at least eighteen years of age on or before the date of the election and has provided satisfactory evidence of citizenship as prescribed in section 16-166, shall be deemed a qualified elector for any purpose for which such qualification is required by law, except as provided in section 16-126. A person continues to be a qualified elector until that person's registration is canceled pursuant to section 16-165 or until that person does not qualify as a resident as defined in section 16-101, subsection B.
B. For purposes of subsection A of this section, a person who does not reside at a fixed, permanent or private structure shall be properly registered to vote if that person is qualified pursuant to section 16-101 and if that person's registration address is any of the following places located in this state:
1. 1. A homeless shelter to which the registrant regularly returns.
2. 2. The place at which the registrant is a resident.
3. 3. The county courthouse in the county in which the registrant resides.
4. 4. A general delivery address for a post office covering the location where the registrant is a resident.
C. A person who is otherwise qualified to register to vote shall not be refused registration or declared not qualified to vote because the person does not live in a permanent, private or fixed structure.
D. For the purposes of this section, "homeless shelter" means a supervised publicly or privately operated shelter designed to provide temporary living accommodations to individuals who lack a fixed, regular and adequate nighttime residence.