The 2026 California ADU Law Changes a South Bay Landlord Actually Needs to Know

Published August 10, 2026

Three chaptered 2025 bills reshape ADU permitting for 2026. SB 543 rewrites how livable space is measured and adds a 15 day permit clock, AB 1154 narrows JADU owner occupancy and sets a 30 day minimum rental, and AB 462 lets fire damaged lots get an ADU occupancy certificate first.

The short answer

Three 2025 bills change California ADU permitting for 2026. SB 543 (Chapter 520, Statutes of 2025) redefines livable space to exclude wall thickness, exempts ADUs and JADUs under 500 square feet of interior livable space from school impact fees, and gives permitting agencies 15 business days to flag an incomplete application or it is deemed complete. AB 1154 (Chapter 507) limits mandatory JADU owner occupancy to units that share a bathroom or kitchen with the main house and adds a 30 day minimum JADU rental term. AB 462 (Chapter 491) lets a fire or disaster damaged lot get its ADU certificate of occupancy before the main house's, in declared emergencies from February 1, 2025 forward.

Last verified: August 10, 2026

The bigger context: the ADU statute moved

If you learned California ADU law from Government Code section 65852.2, that citation is now out of date. The legislature recodified the ADU framework out of section 65852.2 and its companion JADU section 65852.22 into a new block starting at Government Code section 66310, added by Statutes of 2024, Chapter 7, effective January 1, 2025. The rules did not change substantively in that move, but the citations did. Ministerial approval categories now live at section 66323, definitions at section 66313, permit timelines at section 66317, and JADU rules at section 66333. If a contractor or online guide cites 65852.2 as current law, check the source date.

SB 543: the cleanup bill that actually bites

SB 543, authored in the 2025-2026 session, was approved by the governor and chaptered on October 10, 2025 as Chapter 520, Statutes of 2025. Most of its provisions take effect January 1, 2026.

Livable space, not gross square footage. SB 543 defines "livable space" in Government Code section 66313 as space intended for human habitation, including living, sleeping, eating, cooking, or sanitation, and ties the JADU size cap and other measurements to interior livable space rather than the building's outer dimensions. That resolves a real dispute: cities that measured to the outside of exterior walls were shrinking a builder's usable square footage compared to cities that measured to the inside face. Interior livable space is now the statewide yardstick.

School fees waived under 500 square feet. Under the amended framework, an ADU or JADU with less than 500 square feet of interior livable space does not count as space that increases a district's assessable square footage under Education Code section 17620, the statute districts use to charge developer fees. A small ADU or JADU should not trigger a school impact fee at all. Larger units are still assessed, and the fee schedule is set locally, so verify the number with your district before you assume zero.

A hard clock on permit review. Government Code section 66317, as amended by SB 543, requires a permitting agency to determine whether an ADU application is complete and give written notice within 15 business days of receiving it. Miss that window and the application is deemed complete by operation of law. The agency then has 60 days from a completed application to approve or deny it ministerially, and if it does neither, the application is deemed approved. An appeal of a denial gets a final written determination within 60 business days. For an owner used to permit review dragging on with no clear deadline, this is a real backstop.

Fire sprinklers cannot be required for a JADU unless the primary residence itself is required to have them, per section 66323(d). JADU ordinances must clear HCD. Local agencies now have to submit their JADU ordinances to the Department of Housing and Community Development within 60 days, and a noncompliant ordinance can be rendered null and void, pushing the jurisdiction back onto the state's default ministerial standards.

AB 1154: JADU owner occupancy gets narrower

AB 1154 was approved and chaptered the same day as SB 543, October 10, 2025, as Chapter 507, Statutes of 2025, amending Government Code section 66333.

Before this bill, the general expectation was that a homeowner converting part of a single-family house into a JADU had to live on site. AB 1154 ties that requirement specifically to plumbing. Owner occupancy is required only if the JADU shares sanitation facilities, meaning the bathroom or kitchen, with the rest of the house. A JADU with its own separate bathroom and kitchen does not trigger it. The requirement is also waived where the owner is a governmental agency, land trust, or qualified nonprofit housing organization.

AB 1154 also writes a 30 day minimum rental term into section 66333 for JADUs, closing off short-term rental use of a converted bedroom or in-law suite.

AB 462: disaster rebuild gets an exception

AB 462, Chapter 491, Statutes of 2025, was approved October 10, 2025, and carried an urgency clause, so it took effect immediately on signing rather than waiting for January 1, 2026. It amends Government Code sections 66328 and 66329.

The general rule in section 66328 is that a local agency cannot issue a certificate of occupancy for an ADU before the primary residence has one. AB 462 creates a narrow exception. In a county under a state of emergency proclaimed by the governor on or after February 1, 2025, where the primary dwelling was substantially damaged or destroyed and the ADU has passed its required inspections, the agency can issue the ADU's certificate of occupancy first. The exception does not apply to an attached ADU, only a detached one, since an attached unit is structurally part of the house it would otherwise wait on.

This is not a day to day issue for most owners, but it matters for anyone who has lost a primary structure to fire and has a detached ADU still standing.

What this means for a South Bay owner in 2026

| Bill | Chapter | Approved | Effective | What changes |

|---|---|---|---|---|

| SB 543 | Ch. 520, Stats. 2025 | Oct. 10, 2025 | Jan. 1, 2026 | Livable space definition, small unit school fee exemption, 15 business day completeness clock, JADU fire sprinkler exemption |

| AB 1154 | Ch. 507, Stats. 2025 | Oct. 10, 2025 | Jan. 1, 2026 | JADU owner occupancy tied to shared sanitation only, 30 day minimum JADU rental term |

| AB 462 | Ch. 491, Stats. 2025 | Oct. 10, 2025 | Immediate (urgency) | Detached ADU can get certificate of occupancy before a disaster damaged primary residence in a declared emergency |

None of these three bills change the core ministerial approval right, the multifamily lot detached ADU allowance, or the setback and height standards already in place. They tighten timelines, clarify measurement, and narrow one occupancy rule. If your city's ADU handout still cites the old 65852.2 numbering or describes JADU owner occupancy as absolute, it is out of date and worth a call to the planning department.

FAQ

Do I need to resubmit a pending ADU permit because of these changes?

Not automatically. These are prospective changes to the timelines and standards agencies must follow. Ask your city's building department how it applies the new completeness and approval clocks to applications already in the queue.

Does the school fee exemption mean I never pay a school fee on an ADU?

No. It applies only to units under 500 square feet of interior livable space. A larger ADU is still assessed at a locally set rate.

Can my JADU tenant sign a month to month lease?

Yes, as long as the term exceeds 30 days rather than functioning as a nightly or weekly stay, per section 66333 as amended by AB 1154.

Is the old citation to Government Code section 65852.2 still valid?

No. The substance mostly carried over, but the numbering moved to a new block starting at section 66310, effective January 1, 2025. Treat any document still citing 65852.2 as potentially stale.

Does AB 462's disaster exception apply anywhere in the South Bay?

Only within a county under a gubernatorial state of emergency proclaimed on or after February 1, 2025, where the primary residence was substantially damaged or destroyed. Confirm current proclamation status and coverage with your city's building department.

This article is general information about California ADU statutes, not legal or permitting advice for your property. Confirm current requirements with a licensed contractor, land use attorney, or your city's building department before you file.

Topics: compliance, ADU, South Bay, landlord compliance, permitting, property management

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