California ADU Laws 2026 — What Every Homeowner Needs to Know

June 2026 · Updated October 2026 · 7 min read · By ADU Intelligence Systems

One new ADU law, SB 543, took effect January 1, 2026. Two 2023 laws still shape what you can build. SB 79, a housing law that is not an ADU law, applies near certain transit stops from July 1, 2026.

The short version

The key rules to know in 2026:

• SB 543 requires a decision on whether an ADU application is complete within 15 business days, and spares units under 500 sq ft of interior space from school fees
• Since 2024, owner-occupancy requirements for ADUs are permanently removed (AB 976, enacted 2023); a JADU that shares a bathroom with the house still requires owner-occupancy (Gov. Code §66333(b)).
• Under AB 1033 (2023), a city or county may adopt an ordinance allowing an ADU to be sold separately as a condo

SB 543 — A completeness deadline, and no school fees under 500 sq ft

SB 543 changed several ADU rules. Two matter most for a typical homeowner:

A completeness deadline. Local agencies must decide whether your ADU application is complete within 15 business days and give you a written list of anything missing, with how to fix it. If they miss that deadline, the application is deemed complete.

No school fees for ADUs under 500 sq ft. For additions to an existing home, school fees apply only when the added space is over 500 sq ft. SB 543 treats an ADU or JADU with less than 500 sq ft of interior livable space as below that line, so no school fee applies. Ask your school district for its current rate if your unit is larger.

What this means for you: If you are planning a studio or one-bedroom ADU, keeping it under 500 sq ft of interior space avoids the school fee. The 15-business-day completeness deadline applies to every ADU application.

AB 976 — Owner-occupancy requirement permanently removed

Previously, California had temporarily suspended owner-occupancy requirements — meaning you did not have to live on the property to build or rent an ADU. AB 976 makes this permanent.

This matters most for investors and homeowners who want to rent out both the primary residence and the ADU, or who plan to eventually move out. Under the old rules, renting both units could trigger compliance questions. That ambiguity is now gone.

What this means for you: You can build an ADU on a property you do not currently live in. You can rent out both units simultaneously. You can leave the property entirely without violating any ADU occupancy condition.

AB 1033 — Sell your ADU as a separate condo (in participating cities)

AB 1033 is the most financially significant law for long-term property strategy. It applies only where a city or county has adopted an ordinance; check with your city before designing for a separate sale.

Under AB 1033, if your city has opted in, you can build an ADU and later sell it as a separate condominium — independently from the primary residence. Your lot becomes a two-unit ownership structure, similar to a small condo development.

What this means for you: Your ADU becomes not just a rental income stream but a separate saleable asset. Build it, hold it as a rental for several years, then sell it independently as an entry-level condo. This dramatically changes the long-term financial model of ADU construction in participating cities.

Check whether your city has adopted AB 1033 before designing your project — the structural and HOA requirements for a separable condo unit differ from a standard ADU.

Also new in 2026 (not an ADU law): SB 79

SB 79 applies to housing development near transit stops as the law defines them, starting July 1, 2026. Whether it affects a given property depends on its location and on how the city applies it; check with your city's planning department.

What has not changed

The fundamental ADU rights established by SB 9, AB 68, AB 2221, and AB 976 remain fully in effect:

• 4-foot rear and side setbacks for detached ADUs
• Maximum ADU size of 1,200 sq ft on most residential lots
• 60-day permit approval deadline for compliant applications
• No replacement parking required when converting a garage
• Up to 3 units permitted on many single-family lots (primary + ADU + JADU)

Before you hire an architect or contractor

SB 543 adds two rules: a 15-business-day deadline for deciding whether an ADU application is complete, and no school fee for an ADU or JADU with less than 500 sq ft of interior livable space. Your property still has to meet zoning, setback and overlay requirements; a flood zone, fire hazard severity zone or local rule can still stop a project that looks feasible on paper.

Run a feasibility check on your address before spending money on plans. An ADUVerify report identifies the specific flags on your parcel — flood zone, fire zone, zoning conflicts, setback constraints — in minutes, before you commit to an architect or permit application.