Informational only, not legal advice. ADU rules change often and differ by city. Confirm with your local planning department before you rely on anything here.
AB 1621, by Assemblymember Lori Wilson (D-Suisun City), was signed by Governor Newsom on September 29, 2026 and chaptered as Chapter 780, Statutes of 2026. It targets the stage of a housing project that most delays builders after the hard part is supposedly over: the building permit. Starting January 1, 2027, a city generally can't require more than two rounds of plan check on a building permit for a housing development, can't change approved plans during inspections, must decide permit appeals in half the time, and violating any of it now counts as a violation of the Housing Accountability Act.
If you already have your entitlement (or your project is by-right) and you're waiting on building permits, 2027 brings a limit on endless correction cycles: two plan check reviews, with exceptions the bill specifies, then the city either approves or denies. Appeals of a permit decision must be decided within 30 business days for 25 units or fewer. Because a violation is now a Housing Accountability Act violation, you have a much stronger remedy. Keep every correction letter and resubmittal date. Not legal advice; a land-use attorney should confirm how the rules apply to your permit.
The postentitlement permit law, before and after AB 1621
California already has a permit shot clock for this phase. Government Code section 65913.3, added in 2022, covers "postentitlement phase permits": the nondiscretionary permits you need after your project is approved, such as building, demolition, grading and minor offsite improvement permits, for a development that is at least two-thirds residential. The city has 15 business days to decide whether an application is complete, then 30 business days (25 units or fewer) or 60 business days (26 units or more) to finish its review.
The gap: the clock measured each review, not the number of reviews, so a fifth round of comments simply restarted it. AB 1621, per its Legislative Counsel's digest, closes that gap.
| Rule | Through December 31, 2026 | From January 1, 2027 (AB 1621) |
|---|---|---|
| Plan check rounds | No limit | No more than two plan check and specification reviews, except as the bill specifies; then the city may deny, and the applicant may ask to resubmit |
| Changes during inspection | Not addressed | City can't require changes that deviate from the approved plans, except as specified |
| Appeal decision, 25 units or fewer | 60 business days | 30 business days |
| Appeal decision, 26 units or more | 90 business days | 45 business days |
| Outside agency review | Tolls the clock broadly | Tolls only when federal or state law requires another independent public agency's review, and the city must tell you |
| Enforcement | Writ of mandate | Writ of mandate, and a violation is now a Housing Accountability Act violation |
Why the Housing Accountability Act piece matters
The Housing Accountability Act is the state's strongest anti-delay statute. It limits when a city can deny or shrink a qualifying project and carries real penalties. AB 1621 expands the Act's definition of "disapprove the housing development project" to include any failure to follow the postentitlement permit rules. So a city that runs a sixth round of plan check, or rewrites approved plans at framing inspection, is no longer just missing a deadline; it can be treated as having disapproved the project.
The bill also lets you go to court for a writ of mandate to compel approval if an appeal is denied, not decided on time, or the city has no appeal process at all. The digest does not describe a "deemed approved" remedy, so don't assume a permit issues itself when a clock runs out.
What still stops the clock
Only a review by another independent public agency that federal or state law requires. If a city says it is waiting on someone, ask in writing which law requires it.
Does AB 1621 apply to an ADU permit?
Partly, and carefully. A standalone ADU added to a lot already has its own clock under state ADU law: the city must act on a complete ADU permit application within 60 days, and since 2026 must do its first completeness review within 15 business days (see our 2026 ADU law guide and ADU permit process guide). Section 65913.3 itself names ADUs only once, requiring cities to post sample complete applications for several project types, including an ADU.
Where AB 1621 clearly helps is the larger projects we build: an SB 1211 multifamily ADU project bundled with other work, a small-lot subdivision under SB 684 or SB 1123, an SB 9 duplex, or a townhome project under AB 1751. Those are housing developments that get an approval and then live or die in building plan check. Whether the two-review cap also reaches a single backyard ADU permit is a question your city attorney or a land-use attorney should answer; the statute doesn't say directly.
How to use the new rules
- Submit a complete set. The two-review cap protects you, but it also means a city can deny after round two. A thin first submittal wastes one of your two rounds.
- Track dates in business days. Log the submittal date, the completeness letter and each correction letter. Those dates are your evidence.
- Answer every comment in round two. If the city then issues a third round on items it never raised before, cite Government Code section 65913.3 as amended by AB 1621 in your reply.
- Hold the approved plans at inspection. If an inspector asks for something that deviates from the approved set, ask for it in writing and reference the new rule.
Our recommendation: for any project you plan to permit in 2027, build the two-round limit into your schedule and choose a designer who submits complete sets. Rules vary by city on how they count a "review," so check with your building department how it will implement AB 1621 before you rely on it.
Frequently asked questions
How many plan check rounds can a California city require for a building permit?
Under AB 1621, from January 1, 2027, a city generally can't require or request more than two plan check and specification reviews on a postentitlement building permit for a housing development, with exceptions the bill specifies. After two rounds it can deny a noncompliant application, and the applicant may ask to resubmit.
What is a postentitlement phase permit?
A nondiscretionary permit issued after a housing project is approved, such as a building, demolition, grading or minor offsite improvement permit, for a development that is at least two-thirds residential (Government Code section 65913.3).
How long does a city have to decide a building permit appeal in 2027?
30 business days for projects of 25 units or fewer and 45 business days for 26 units or more, down from 60 and 90.
Does AB 1621 apply to ADU permits?
Standalone ADU permits already have their own 60-day decision clock under state ADU law. AB 1621 clearly covers housing developments in building plan check; whether its two-review cap also reaches a single ADU permit is a question for your city or a land-use attorney.
Official bill text
- AB 1621 — Planning and Zoning Law: postentitlement phase permits: Housing Accountability Act. (official bill text, California Legislative Information)
- SB 1211 — Land use: accessory dwelling units: ministerial approval. (official bill text, California Legislative Information)
- SB 684 — Land use: streamlined approval processes: development projects of 10 or fewer residential units on urban lots under 5 acres. (official bill text, California Legislative Information)
- SB 1123 — Planning and zoning: subdivisions: ministerial review. (official bill text, California Legislative Information)
- SB 9 — Housing development: approvals. (official bill text, California Legislative Information)
- AB 1751 — Missing Middle Townhome Ownership Act. (official bill text, California Legislative Information)
Sources
- AB 1621 (2025-26): status, digest and chaptered text — Chapter 780, Statutes of 2026; two plan check reviews; appeal deadlines 30/45 business days; HAA definition expanded; Gov. Code § 65913.3 time limits
- Governor Newsom signs housing legislation (September 29, 2026) — Signing release listing AB 1621 by Assemblymember Lori Wilson
- HCD ADU Handbook and 2026 Addendum — ADU permit timelines under state ADU law
- AB 1621
- plan check limit California
- postentitlement phase permits
- building permit delays California 2027
- Housing Accountability Act permits
- Government Code 65913.3
- how many plan check rounds California
- building permit appeal deadline
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Informational only. Not legal, architectural, or investment advice. Confirm current rules with your local planning department.