Casitas in rural Arizona: small towns, unincorporated land, and county rules

Two laws, two different scopes

Arizona actually passed two casita laws, and they cover different kinds of land:

• HB 2720 (2024, effective January 1, 2025) applies to municipalities with populations over 75,000. That's Phoenix, Mesa, Scottsdale, Tucson, Chandler, Gilbert, Tempe, Glendale, and a handful of others. See our full HB 2720 explainer.
• HB 2928 (signed May 2025), sometimes called the Casita Reform Act, extended nearly identical ADU requirements to counties across Arizona. It applies to unincorporated county land with no population threshold.

The gap that catches rural readers

If you live in a small incorporated town under 75,000 people — Payson, Prescott, Sedona, Show Low, Cottonwood, Bisbee, Page, Camp Verde, and many others — neither state law may force that town to allow your casita. HB 2720 doesn't reach it because the town is too small. HB 2928 governs county land, not incorporated towns.

Those towns may still allow ADUs under their own local zoning — many do — but they are not compelled by the state statute. This is the single most important thing to understand before you spend money on plans: in a small town, you're negotiating with local code, not standing on state preemption.

Unincorporated county land is the opposite story

If your property is outside any town's limits — unincorporated Gila, Yavapai, Coconino, Navajo, Pinal, Maricopa, or Pima county land — HB 2928 applies. Counties were required to adopt compliant ADU regulations by January 1, 2026. If a county failed to do so, ADUs are permitted on all residentially zoned lots without those limits.

The state baseline that counties must honor mirrors the municipal rules:

• At least one attached ADU and one detached ADU allowed wherever a single-family home is allowed.
• A possible additional affordable unit on parcels of 1 acre or more, if deed-restricted as affordable.
• Five-foot minimum setbacks, no extra parking requirement, no owner-occupancy mandate, and the standard size caps.

Payson and Gila County: how the distinction plays out

Payson is an incorporated town well under 75,000 people, so the state's municipal ADU mandate doesn't reach it — the Town of Payson sets its own ADU/guest house rules through local zoning. Unincorporated Gila County land around Payson falls under HB 2928 and Gila County's implementation of it instead. Two different authorities, two different rulebooks, sometimes across the street from each other. Confirm current requirements with the Town of Payson and Gila County Community Development respectively before designing.

How to tell which set of rules applies to you

1. Find out whether your address is inside town limits or unincorporated. The county assessor or the town's planning department can confirm in a single phone call.
2. If you're inside a town under 75,000, ask the town directly what its ADU or "guest house" zoning allows. You're working with local code, not state law.
3. If you're unincorporated, contact the county planning department and ask how they implemented HB 2928.
4. Budget for rural site costs. A private well, a septic system, and long utility runs from the road to the pad don't show up on metro casita bids. Get those quoted before you draw plans — see the cost guide for the metro baseline you'll be adding to.

Before you build

Even where state law is on your side, private restrictions can still stop you. If your rural lot is in a subdivision with recorded CC&Rs, read our HOA rules guide — the state statute doesn't override private covenants. And line up money before you line up a builder: the financing guide walks through HELOCs, cash-out refis, renovation loans, and construction-to-permanent loans and how each one handles a rural build.

Frequently asked questions