Every Senate and Assembly bill that shapes your backyard ADU, from the 60-day rule to the two-ADU law coming January 1, 2027, in plain English.
The short answer
California's ADU laws (Government Code §§ 66310–66342) give most homeowners the right to build a backyard home. Your city must approve a qualifying ADU without a hearing, decide within 60 days, allow at least 800 sq ft, and skip impact fees at 750 sq ft or less. You needn't live on site, and your HOA can't say no.
to approve or deny a complete application, or it's deemed approved (§ 66317)
ADU your city must allow with 4-foot setbacks (§ 66321)
impact fees on an ADU of 750 sq ft or less (§ 66311.5)
new detached ADUs per single-family lot from January 1, 2027 (AB 956)
Until 2020, a California city could take 120 days to act on an ADU permit, require the owner to live on the lot, and charge impact fees on even a tiny cottage.
Almost none of that survives in 2026. A decade of Senate and Assembly bills turned the ADU from a favor your city might grant into a right with deadlines. In 2024, California permitted 30,354 ADUs, up from 1,336 in 2016, according to the state housing department (HCD). Here's each law that matters, and what it means for your lot.
Which California ADU bills matter most?
More than 20 bills since 2016 built today's rules. Most took effect on January 1 after they passed, so check again every January.
| In effect | Bill | What it means for you |
|---|---|---|
| 2017 | SB 1069, AB 2299 | "Second units" became ADUs, approved without a hearing. |
| 2020 | AB 68, AB 881, SB 13 | Review time fell from 120 to 60 days; setbacks capped at 4 feet; owner-occupancy rules paused. |
| 2020 | AB 670 | An HOA can't ban or unreasonably restrict an ADU. |
| 2021 | AB 3182 | If the city misses the 60-day deadline, your permit is deemed approved. |
| 2022 | SB 9 | You may split a single-family lot and build two homes on each half. |
| 2023 | AB 2221, SB 897 | Only objective standards apply, and detached ADUs get 16 to 18 feet of height. |
| 2024 | AB 976, AB 1033, AB 1332 | No owner-occupancy rule, ever; optional ADU condos; pre-approved plans in every city by 2025. |
| 2025 | AB 2533, SB 1211 | Older unpermitted ADUs are easier to legalize; apartment lots get up to eight detached ADUs. |
| 2025 | AB 130, AB 462 | HOAs can't charge ADU fees; coastal ADU permits get a 60-day clock. |
| Jan. 1, 2026 | SB 543, AB 1154, SB 9 (2025) | A 15-business-day completeness check, size measured as interior living space, new JADU rules. |
| Jan. 1, 2027 | AB 956, SB 1117 | Two detached ADUs per single-family lot; smaller fees above 750 sq ft. |
Sources: HCD ADU Handbook (March 2026); bill texts on leginfo, checked October 8, 2026.
Don't mix up the two SB 9s
The 2021 SB 9 is the lot-split law. A 2025 bill with the same number voids any city ADU ordinance not properly filed with HCD.
How fast does my city have to approve an ADU?
Your city has 15 business days to say whether your application is complete, then 60 days to approve or deny it. Miss either deadline, and the application is treated as complete, or approved.
"If the local agency has not approved or denied the completed application within 60 days, the application shall be deemed approved."
— California Government Code § 66317(a)(3)
Approval is ministerial: no hearing, no neighbor vote, no subjective test of neighborhood character. Since January 1, 2026 (SB 543), an incomplete notice must list every missing item, the city can't add new ones later, and you get a written appeal.
Pro tip
Under AB 1332, every city must run a pre-approved ADU plan program and post approved plans online. A detached ADU built from one gets a decision within 30 days instead of 60.
How big and how tall can an ADU be in California?
At least 800 sq ft with 4-foot side and rear setbacks. A city's maximum can't be under 850 sq ft, or 1,000 sq ft with two or more bedrooms.
Lot coverage, floor-area, front-setback, or lot-size rules can't block an 800 sq ft ADU.
Gov. Code § 66321(b)(3)4 feet maximum from side and rear lines; none for a conversion.
Gov. Code § 66314(d)(7)At least 16 feet; 18 feet near major transit, plus 2 feet to match your roof pitch.
Gov. Code § 66321(b)(4)25 feet or your house's zone limit, whichever is lower.
Gov. Code § 66321(b)(4)(D)Since 2026, size means interior livable space (SB 543). Every Bay Modular model, from the 8' × 15' Backyard Studio to the 640 sq ft 2 Bedroom ADU, fits under both the 800 sq ft floor and the 750 sq ft fee line.
Do I need to add parking for an ADU?
Often, no. Cities can't require parking within half a mile's walk of public transit, in a historic district, for a conversion, or within one block of a car-share vehicle.
Elsewhere, the cap is one space per unit or bedroom, whichever is less; tandem counts. Convert or tear down a garage for the ADU, and the city can't make you replace that parking (Gov. Code §§ 66314, 66322).
What fees can a city charge for an ADU?
At 750 sq ft or less, no impact fees. Under 500 sq ft, no school fees. Utility connection charges must be proportionate.
Impact fees
None on an ADU with 750 sq ft of interior livable space or less. Above that, fees scale to your main house.
Gov. Code § 66311.5(c), as of January 1, 2026Over 750 sq ft
From January 1, 2027, impact fees on up to two larger ADUs apply only to the square footage above 750.
SB 1117, Chapter 809, Statutes of 2026School fees
An ADU under 500 sq ft of interior space doesn't trigger school-district fees.
Gov. Code § 66311.5(c)(3)Utility connections
A separate connection, if required, is priced by size or plumbing fixtures. Conversions need no new one.
Gov. Code § 66311.5(b), (e)Plan-check and permit fees still apply; see our 2026 ADU cost guide.
Do I have to live on the property, and can I sell the ADU?
No, you don't have to live there: AB 976 permanently banned owner-occupancy rules for ADUs. A separate sale works only as a condo, in a city that opts in under AB 1033.
A junior ADU (up to 500 sq ft inside your house) differs: since 2026, the owner must live on site only if it shares a bathroom with the house (AB 1154).
ADU condos also need a safety inspection and written consent from every lender on your title (Gov. Code § 66342). Ask your planning department before you count on a sale.
Can I rent my ADU on Airbnb?
Often not. Your city may require ADU rentals of 30 days or longer, and units approved under the state fast track (§ 66323) must be rented for more than 30 days.
Since 2026, junior ADUs can't be short-term rentals at all (§ 66333(g)). Long-term rentals are allowed; see our step-by-step rental guide.
Can my HOA stop me from building an ADU?
No. Under Civil Code §§ 4751 and 714.3, rules that ban or unreasonably restrict an ADU on a single-family lot are void. An HOA may set reasonable design standards, and that's about it.
Per HCD, an HOA can't take part in your city's approval, require neighbors' sign-off, or stall past 60 days. Since June 30, 2025 (AB 130), it can't charge ADU fees either.
What if I already have an unpermitted ADU?
If it was built before January 1, 2020, your city can't deny a permit over code or zoning violations unless the unit is unsafe ("substandard") (AB 2533, Gov. Code § 66311.7).
It can't penalize you for the unit and generally can't charge impact or connection fees. A licensed contractor can do a confidential inspection first.
How do SB 9 lot splits work with ADUs?
SB 9 lets you split a single-family lot into two and build up to two homes on each. If you split, each new lot is capped at two units total, ADUs included.
Each new lot must be at least 40% of the original and 1,200 sq ft, and you must plan to live in one home for three years (Gov. Code § 66411.7). From 2027, AB 2601 lets the split and the homes be processed together.
Own apartments? SB 1211 allows up to eight detached ADUs, but no more than the existing units.
What's new in 2026, and what changes in 2027?
The January 1, 2026 laws (SB 543, AB 1154) sped up paperwork and reset fee math. Two bills signed on September 29, 2026 take effect January 1, 2027.
- AB 956. Cities must approve two new detached ADUs on a single-family lot, each up to 800 sq ft if the city caps size. With both built, a JADU is optional for the city.
- SB 1117. Impact fees on ADUs over 750 sq ft apply only to the footage above 750.
Solar, too
New detached ADUs need solar under the Energy Code, but the panels can go on your main house. Conversions don't.
Not sure what your lot allows?
We'll check your city's rules, buildable area, and delivery access. Free, no obligation.
Frequently asked questions
What is the new ADU law in California for 2026?
SB 543 and AB 1154 took effect January 1, 2026: a 15-business-day completeness check, size measured as interior living space, no impact fees up to 750 sq ft, and no short-term rentals of junior ADUs.
Can I build two ADUs on my lot in California?
Today, one new detached ADU plus a converted ADU and a JADU within existing space (§ 66323). From January 1, 2027, AB 956 allows two new detached ADUs.
How long does a city have to approve an ADU?
Sixty days after a complete application. If the city misses it, the application is deemed approved (§ 66317).
Can I sell my ADU separately from my house?
Only as a condo, in a city with an AB 1033 ordinance, with lender consent. Otherwise you can rent it, not sell it.
Do these laws apply to a factory-built ADU?
Yes, the same rules apply. The state oversees the factory build; your city inspects the foundation and hookups. See what factory-built housing is.
Find out what California law lets you build
We'll review your lot and your city's ADU rules, then show the models that fit and their all-in prices. Free, no obligation.
About Bay Modular Team
Bay Modular is a California factory-built housing manufacturer (HCD #1585366). We design and build backyard ADUs in our factory in Lathrop, CA, and install them across California. More about us
Sources
- California Department of Housing and Community Development (HCD), Accessory Dwelling Unit Handbook, March 2026.
- Gov. Code § 66311.5, § 66314, § 66317, § 66321, § 66323, § 66342, § 66411.7; Civ. Code § 4751. Accessed October 8, 2026.
- 2026 bills AB 956 (Ch. 791), SB 1117 (Ch. 809), AB 2601 (Ch. 955); SB 543 (Ch. 520). Accessed October 8, 2026.
- California Energy Commission, 2025 Energy Code ADU FAQs.
This guide is general information, not legal advice. ADU rules change often and cities add their own standards; confirm details with your city's planning department before you design or apply.
