Arizona

Arizona passed legislation in 2023 requiring cities and towns to allow accessory dwelling units on lots zoned for single-family housing. Phoenix, Tucson, Scottsdale, and Flagstaff have all updated their codes accordingly. ADU Pass helps Arizona homeowners work through the permit paperwork that comes with this new statewide right to build.

524 ZIP codes
17 Counties
232 Cities

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State ADU details

State ADU law

Arizona has enacted statewide ADU preemption in two waves. HB 2720 (signed 2024-05-21, codified at A.R.S. § 9-416.18) requires every Arizona municipality with population of at least 75,000 to permit ADUs on single-family parcels by 2025-01-01: at least one attached and one detached ADU on every single-family lot, plus a third detached ADU on lots one acre or larger if at least one unit is income-restricted. HB 2928 (signed 2025-05-28) extends the same regime to counties, with a 2026-01-01 compliance deadline; counties that fail to adopt compliant regulations by that date must allow ADUs by-right on every residential parcel. Both bills cap ADU size at the lesser of 75% of the primary dwelling's gross floor area or 1,000 sqft, prohibit additional parking requirements, prohibit design-matching mandates, set a 5-foot maximum side and rear setback, prohibit additional impact fees keyed to ADU status, and forbid public-street-improvement conditions. Owner-occupancy may be required by a city or county only when the ADU is operated as a short-term or vacation rental and only for ADUs constructed on or after 2024-09-14. Critically, both bills explicitly preserve the enforceability of private CC&Rs, so HOAs may continue to ban ADUs.

checked 2026-04-26

State financing programs

Arizona does not operate an ADU-specific statewide loan, grant, or forgivable-loan program. The Arizona Department of Housing (ADOH) administers the State Housing Trust Fund, federal HOME and CDBG pass-through, the federal Low-Income Housing Tax Credit allocation, and the Arizona is Home down-payment-assistance and mortgage product line. None target ADU construction directly, though an ADU-bearing primary residence can qualify for the underlying mortgage when other eligibility criteria are met. The Arizona Industrial Development Authority issues mortgage credit certificates and revenue bonds that can flow through to ADU-bearing properties on the same basis as conventional homes.

checked 2026-04-26

State insurance regimes

Arizona does not operate a state FAIR plan, wind pool, or earthquake insurance program. The Arizona Department of Insurance and Financial Institutions (DIFI, https://difi.az.gov/) regulates standard homeowners and dwelling-fire products under Arizona Revised Statutes Title 20. The principal ADU-relevant exposure is wildfire in the wildland-urban interface (WUI), particularly in Yavapai, Coconino, Gila, and parts of Pima and Pinal counties. Arizona's overall non-renewal rate (~0.8% in 2023) is well below California (1.72%) or Florida (2.99%), but localized non-renewal pressure is rising in WUI areas; carriers point to Cohesive Wildfire Strategy and Firewise USA documentation when underwriting. The state has no admitted insurer of last resort; surplus-lines carriers and specialty programs (Foremost, AIG Private Client, Chubb Wildfire Defense Services) cover the high-risk gap.

checked 2026-04-26

State housing programs

Arizona's state-level ADU programs work through the HB 2720 / HB 2928 preemption framework rather than through a separate pre-approved-plan catalog or fee-waiver statute. The state itself does not maintain an ADU plan library, but HB 2720 and HB 2928 effectively waive impact fees keyed to ADU status by prohibiting cities and counties from imposing them. Pre-approved plan libraries are emerging at the city level (Tempe received a 2025 AARP Community Challenge Grant for an ADU Design Challenge that will populate its standard plan library). No statewide ministerial-approval timeline mandate exists beyond the general preemption requirements; cities and counties retain discretion over the review process so long as they do not impose conditions HB 2720/2928 forbids.

checked 2026-04-26

Known state issues (2)

  • policy-review (since 2026-01) — Practitioners working in Arizona unincorporated areas should verify each county's current ADU ordinance status; many counties are mid-implementation or operating under default rules pending ordinance adoption. (source)
  • policy-review (since 2024-05) — ADU pathway in Arizona is bifurcated: parcels outside an HOA enjoy strong state-level by-right access; parcels inside an HOA depend entirely on the declaration and can be effectively prohibited. (source)
Federal (United States) — ADU-relevant rules and programs

Federal ADU law

The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.

checked 2026-04-20

Federal financing programs

Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.

checked 2026-04-20

Federal tax credits

There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.

checked 2026-04-20

Federal housing programs

HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.

checked 2026-04-20

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