Arizona House Majority Leader Michael Carbone, a Buckeye Republican, saw his bill limiting county regulations for backyard casitas or accessory dwelling units succeed when it was signed into law last week.
House Bill 2928, signed by Gov. Katie Hobbs, provides counties with restrictions and guidelines on residents seeking to develop additional residential units on single-family home lots.
The bill is essentially a follow-up to a bill signed by Hobbs last year that restricted how cities can regulate ADU development.
The new law forbids county restrictions on ADUs—also known as casitas or guest houses—and requires counties to adopt consistent, fair rules allowing both attached and detached ADUs on lots zoned for single-family homes, according to a press release from the state House majority.
“Arizona homeowners should be able to use their property without being buried in red tape,” Carbone said in a release. “Whether it’s a unit for an aging parent, a young adult, or a source of income, ADUs are a practical solution—and it’s time the law recognized that. We spent months working with counties and stakeholders to get this right, and we delivered.”
Carbon and state Republicans claim the law sets statewide standards that prevent counties from blocking ADUs with burdensome parking requirements, design mandates, preexisting relationship rules, or costly construction conditions.
The law will also prohibit excessive fees, unreasonable setbacks, or requirements for unnecessary public improvements that drive up housing costs, according to state republicans.
The law includes exemptions for tribal lands, military areas, high-noise zones, and utility easements. It also allows counties to require septic system evaluations for ADUs not connected to sewer systems. Counties must adopt the necessary regulations by January 1, 2026, or the bill’s default provisions will automatically take effect.
“House Republicans are delivering results,” Carbone added. “This law gives homeowners more freedom, cuts through bureaucracy, and ensures Arizona families can thrive. It’s exactly the kind of policy leadership voters sent us here to provide.”
