Updated September 2026. We keep this page current as new ADU laws take effect, so you don’t have to piece the rules together from a separate article for each year.
California’s ADU laws changed again on January 1, 2026. In short: size limits now count interior livable space, small ADUs skip more fees, a junior ADU with its own bathroom no longer requires you to live on the property, and cities face tighter deadlines. The 2024 and 2025 changes still apply too, including the right to legalize an older unpermitted ADU and, where your city allows it, to sell an ADU separately.
California ADU Laws at a Glance
| Law | In effect | What it means for homeowners |
|---|---|---|
| SB 543 | January 1, 2026 | ADU size limits are measured in interior livable space. ADUs of 750 sq ft or less and JADUs of 500 sq ft or less pay no impact fees, and units of 500 sq ft or less pay no school fees. Cities must tell you within 15 days whether your application is complete. |
| AB 1154 | January 1, 2026 | A junior ADU only requires the owner to live on the property if it shares a bathroom with the main home. ADUs and JADUs can’t be rented for 30 days or less. |
| SB 9 (2025) | January 1, 2026 | A city’s ADU ordinance is void if the city doesn’t send it to the state housing department (HCD) within 60 days of adopting it. This is a different bill from the 2021 SB 9 lot-split law. |
| AB 462 | October 10, 2025 | Coastal cities and the Coastal Commission must decide an ADU’s coastal development permit within 60 days, and a city’s decision can’t be appealed to the Commission. Where a state of emergency was declared on or after February 1, 2025, an ADU can be occupied before a destroyed home is rebuilt. |
| AB 2533 | January 1, 2025 | An unpermitted ADU or JADU built before January 1, 2020 can usually be legalized by meeting health and safety standards, with no penalties or impact fees. |
| SB 1211 | January 1, 2025 | Multifamily properties can add up to eight detached ADUs, as long as that doesn’t exceed the number of existing units. Cities can’t require replacement parking when uncovered spaces are removed for an ADU. |
| AB 1332 | January 1, 2025 | Cities must offer a preapproved ADU plan program, and an application that uses a preapproved plan gets a faster decision. |
| SB 1077 | January 1, 2025 | The Coastal Commission and HCD must publish guidance for ADU permitting in the coastal zone by July 1, 2026. |
| AB 976 | January 1, 2024 | Cities can never require you to live on the property to build or rent an ADU. |
| AB 1033 | January 1, 2024 | Cities may let homeowners sell an ADU separately as a condominium. It only applies where your city has opted in. |
What Changed in 2026
SB 543: size, fees, and faster answers
SB 543 cleans up how ADU rules are applied. Size limits are now measured in interior livable space. The impact fee exemption is spelled out: no impact fees on an ADU of 750 square feet or less or a JADU of 500 square feet or less, and no school fees on units of 500 square feet or less. Cities also have to tell you within 15 days whether your application is complete, and they need a written appeal process if they deny it.
AB 1154: junior ADUs and owner-occupancy
A junior ADU is a unit of up to 500 square feet built inside your home. Until 2026, you had to live on the property to have one. Now the owner-occupancy rule only applies when the JADU shares a bathroom with the main home. Give it its own bathroom and you can rent both the house and the JADU. AB 1154 also confirms that ADUs and JADUs can’t be used as short-term rentals of 30 days or less.
AB 462: coastal permits and fire rebuilds
AB 462 took effect immediately in October 2025. Cities in the coastal zone have to approve or deny an ADU’s coastal development permit within 60 days, and a city’s decision can no longer be appealed to the Coastal Commission. When the Commission itself is the permitting agency, it has the same 60 days, and an application it doesn’t act on is deemed approved. In counties where the Governor declared a state of emergency on or after February 1, 2025, an ADU can get its certificate of occupancy before a substantially damaged or destroyed home is rebuilt, which lets families move back onto their lot sooner. AB 462 does not exempt ADUs from needing a coastal permit; it puts a clock on the decision.
SB 9 of 2025: cities have to file their rules
This is not the 2021 SB 9 that allows lot splits. The 2025 bill says a city’s ADU ordinance is void if the city doesn’t send it to HCD within 60 days of adopting it. If your city’s rules are void, state ADU law applies directly.
The 2025 Changes That Still Matter
AB 2533 is the one most homeowners ask us about. If an ADU or garage conversion was built without permits before January 1, 2020, you can usually legalize it by meeting health and safety standards rather than bringing everything up to current code, and the city can’t charge penalties or impact fees. Our guide to legalizing an unpermitted ADU under AB 2533 walks through the process.
SB 1211 opened up multifamily properties: up to eight detached ADUs, capped at the number of existing units, and no replacement parking when uncovered spaces are removed. AB 1332 requires every city to offer preapproved ADU plans, which shortens review. SB 1077 requires state guidance for ADUs in the coastal zone by July 1, 2026.
The 2024 Changes: Owner-Occupancy and Selling an ADU
AB 976 made the ban on ADU owner-occupancy requirements permanent, so you can rent both your home and your ADU. AB 1033 lets cities allow an ADU to be sold separately as a condominium. It only works where a city opts in. The City of San Diego is one of them, which is covered on our San Diego ADU page.
The Core ADU Rules Every California Homeowner Gets
- A detached ADU can be up to 1,200 square feet, and every city must allow at least 800 square feet.
- A junior ADU can be up to 500 square feet inside the main home.
- Cities must approve or deny a complete ADU application within 60 days, or it is deemed approved.
- Side and rear setbacks can’t be more than 4 feet.
- ADUs of 750 square feet or less pay no impact fees.
- You don’t have to live on the property, unless it is a junior ADU that shares a bathroom with the main home.
- ADUs can’t be rented for 30 days or less.
Your city can add its own rules on top, such as design standards or height limits, as long as they don’t conflict with state law. That is why the same ADU can be simple in one city and slow in the next.
Planning an ADU Under the New Rules?
The laws keep making ADUs easier to permit, but they don’t make the build any simpler. A contractor who has permitted ADUs in your city will know which of these rules your city actually applies and where plan check tends to stall. GreatBuildz matches you with three vetted ADU contractors for free, including specialists in garage conversions, and stays involved until final inspection. For budgeting, start with our ADU cost guide.
Frequently Asked Questions
What are the new ADU laws in California for 2026?
Three took effect on January 1, 2026. SB 543 measures ADU size by interior livable space, confirms that ADUs of 750 sq ft or less pay no impact fees, and requires cities to confirm a complete application within 15 days. AB 1154 limits the JADU owner-occupancy rule to JADUs that share a bathroom with the main home. SB 9 of 2025 voids any city ADU ordinance not sent to the state within 60 days of adoption.
How big can an ADU be in California?
A detached ADU can be up to 1,200 square feet of interior livable space, and every city must allow at least 800 square feet. A junior ADU, built inside the main home, can be up to 500 square feet.
Do I have to live on the property to build an ADU in California?
No. Since AB 976 took effect in 2024, cities can’t require owner-occupancy for an ADU. The only exception left is a junior ADU that shares a bathroom with the main home, under AB 1154.
Can I legalize an unpermitted ADU in California?
Usually, yes. Under AB 2533, an ADU or JADU built without permits before January 1, 2020 can be legalized by meeting health and safety standards rather than every current code, and the city can’t charge penalties or impact fees to do it.
Can you sell an ADU separately in California?
Only where your city has opted in. AB 1033 lets cities allow an ADU to be sold as a separate condominium. The City of San Diego adopted it in 2025 and unincorporated San Diego County in 2026, but most cities have not.
