Arizona Statewide Rule
Arizona ADU Preemption Law (HB 2720) Explained
Key Facts
- Statute
- A.R.S. 9-461.18
- Bill
- HB 2720 (2024)
- Applies To
- Cities over 75,000
- Max Size
- 1,000 sq ft or 75%
- Counties
- HB 2928 (2025) mandate
Summary
Arizona's HB 2720 (2024), codified at A.R.S. 9-461.18, requires municipalities over 75,000 population to permit accessory dwelling units on single-family lots, limiting restrictive zoning, owner-occupancy, and parking mandates. HB 2928 (2025) extends an ADU mandate to counties.
A. A municipality shall adopt regulations that allow on any lot or parcel where a single-family dwelling is allowed all of the following: 1. At least one attached and one detached accessory dwelling unit as a permitted use. 2. A minimum of one additional detached accessory dwelling unit as a permitted use on a lot or parcel that is one acre or more in size if at least one accessory dwelling unit on the lot or parcel is a restricted-affordable dwelling unit. 3. An accessory dwelling unit that is seventy-five percent of the gross floor area of the single-family dwelling on the same lot or parcel or one thousand square feet, whichever is less.
Full Breakdown
Codified at A.R.S. 9-461.18, HB 2720 requires qualifying cities to allow at least one attached, detached, or internal accessory dwelling unit on any lot zoned for single-family use. Cities cannot require owner occupancy, mandate more than one parking space per ADU, impose a larger minimum lot size, or bar separate leasing of the ADU. ADUs up to 1,000 square feet or 75% of the primary dwelling (whichever is less) must be allowed by right. A separate 2025 law, HB 2928 (A.R.S. 11-810.01), extends an ADU mandate to counties for unincorporated single-family lots, with a January 1, 2026 compliance deadline.
Violations & Penalties
Municipal denials inconsistent with the ADU law are subject to civil action and reversal. Property owners may seek declaratory relief and attorney's fees if a city violates the statute.
Frequently Asked Questions
Do all Arizona cities have to allow ADUs?
Can my city require owner occupancy for an ADU?
Sources
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