California’s newest ADU changes come from 2025 legislation that took effect between June 30, 2025 and January 1, 2026. The ones homeowners notice most: permit agencies must rule on whether an ADU application is complete within 15 business days, ADU size limits are now measured by interior livable space, and a junior ADU needs an owner living on the property only if it shares a bathroom with the main house.
The source is the state Department of Housing and Community Development’s ADU Handbook, updated in March 2026, which lists five bills from 2025: AB 1154, SB 9, SB 543, AB 462 and AB 130. Here is what they changed, and what it means if you are planning an ADU now.
The changes that matter for a homeowner
| Change | What the law now says | Government Code section |
|---|---|---|
| Completeness check | The permitting agency decides whether an ADU or junior ADU application is complete and gives written notice within 15 business days; if incomplete, it lists what is missing and how to fix it | 66317(a)(2); 66335(a)(2) |
| Appeals | An applicant can appeal an incompleteness finding or a denial, and the agency gives a final written decision within 60 business days of the appeal | 66317(d); 66335(e) |
| Size limits | Measured by the interior livable space of the ADU or junior ADU | 66321(b)(2) and (b)(3); 66313(d) |
| Impact fees | None from the city or county, a special district or a water company on an ADU of 750 square feet of interior livable space or less, or a junior ADU of 500 or less; above 750, charged in proportion to the main house’s square footage. School districts may still charge fees on units over 500 square feet | 66311.5(c) |
| Junior ADU owner occupancy | Required only if the junior ADU shares sanitation facilities with the main house | 66333(b) |
| Junior ADU rentals | No short-term rentals; if rented, the term must be longer than 30 days | 66333(g) |
| Fire sprinklers | Sprinklers cannot be required in a junior ADU if they are not required for the main house | 66323(d) |
| Local ordinances | A local ADU or junior ADU ordinance not sent to the state within 60 days, or whose city or county does not answer the state’s findings within 30, is null and void, and state ADU law applies until a compliant ordinance is adopted | 66326(d); 66333.5 |
Changes for specific situations
| Situation | What changed |
|---|---|
| Property in the coastal zone | The coastal development permit for an ADU must be approved or denied within 60 days of a complete application (Government Code 66329(a)) |
| Home destroyed in a declared emergency | In a county under a Governor’s emergency proclamation made on or after February 1, 2025, the local agency must issue a certificate of occupancy for a detached ADU before the main house has one, if conditions are met, including that the main house was substantially damaged or destroyed in that event (Government Code 66328) |
| Deed restrictions and CC&Rs | Reasonable restrictions on ADUs in a deed, contract or other instrument cannot include fees or other financial requirements (Civil Code 714.3(b)) |
Renumbered sections
The 2025 legislation also moved three sections of the ADU law. Section 66324, on fees, is now 66311.5; section 66327 is now 66313.5; and section 66332, on legalizing ADUs built without a permit before 2020, is now 66311.7. The rule itself did not change, only a cross-reference was updated, so older articles citing section 66332 still describe it correctly, under the old number. What happens if you build an ADU without a permit covers that rule.
What this means if you are planning an ADU now
An application should get a completeness answer within 15 business days, about three weeks, and if something is missing, the notice has to say what and how to fix it. Completeness is only the first step: in the City of Los Angeles, the median ADU permit issued in 2025 took 122 days from submission to issue (LADBS permit data). Plan sizes against interior livable space. And if the unit stays at 750 square feet of interior livable space or less, the city or county, special districts and water companies cannot charge impact fees on it, though school district fees on units over 500 square feet and utility connection fees are separate matters. For the basics of what counts as an ADU, see what an ADU is under California law.
How we handle it
We design, permit and build ADUs under the current state rules, and in the City of Los Angeles through ADU construction in Los Angeles.
