Assembly Bill 1621 (Wilson, Chapter 780 of 2026) was signed on September 29, 2026 and takes effect on January 1, 2027. It amends the state's rules for housing-related postentitlement permits by barring a local or state agency from requiring or requesting more than two plan check and specification reviews for a covered building-permit application, while allowing the applicant to request additional submittals. It is not an ADU bill by name, and this page explains what it says and how far it reaches.
Government Code section 65913.3 sets deadlines for what the law calls postentitlement phase permits, a category that includes covered building permits, plan checking, building inspection, and other listed permits and reviews for housing development projects. AB 1621 adds a limit on plan check and specification reviews for a building-permit application.
The new text reads: "As part of its review, the local agency or state agency shall not require or request more than two plan check and specification reviews in connection with an application for a building permit."
Two things follow in the same paragraph. After two rounds the agency "may deny an application that is not compliant with the permit standards". And further rounds are the applicant's choice: "An applicant may request additional submittals of applications that are not compliant with the permit standards."
The plan-check limit sits inside the section's 30- and 60-business-day review framework, while AB 1621 separately changes tolling and appeal rules. An agency must say whether an application is complete, in writing, within 15 business days of receiving it.
For housing development projects with 25 units or fewer, the agency then has 30 business days from the date the application is complete to finish its review. It must either return the approved permit application or "return in writing a full set of comments to the applicant with a comprehensive request for revisions".
AB 1621 also addresses the inspector who asks for something different from the approved plans. An agency "shall not request or require any action or inaction as a result of a building inspection" that "would represent a deviation from a previously approved building plan", unless it provides written findings, based on substantial evidence, of one of two things.
The first is that a reasonable person could not read the approved plan as compliant with the standards for the permit. The second is that the deviation "is necessary to address a specific, adverse impact on public health or safety".
If an application is found incomplete, non-compliant or is denied, the agency must offer a written appeal to its governing body. For projects with 25 units or fewer, the agency must give a final written decision on the appeal within 30 business days, down from 60. For larger projects the deadline is 45 business days, down from 90.
If the appeal is denied, is not decided in time, or no appeals process is provided, "the applicant may seek a writ of mandate to compel approval of the application". A local agency that breaks these rules is also in violation of Government Code section 65589.5, the Housing Accountability Act.
The statute is written for postentitlement phase permits. Its definition includes "all building permits and other permits issued under the California Building Standards Code" for the construction or alteration of buildings, and its deadlines are framed around housing development projects.
A stand-alone ADU building permit appears to fit that language, and ADUs keep their own 60-day decision deadline under the ADU statute either way. Because the bill does not mention ADUs by name, ask your building department in writing how it will apply the two-review limit to your application.
The limit is on rounds, not on thoroughness. Apart from the two-round rule, the section "does not place limitations on the amount of feedback" an agency may give or the revisions it may request within a round.
It also cuts both ways. An agency that can no longer ask for a third round may deny an application that is still non-compliant after the second. A complete, well-coordinated first submittal matters more under this rule, not less.
The bill does not change ADU size, height, setback or fee rules. Those are in the ADU statute and, for fees from 2027, in SB 1117.
This page summarises the statute. It is not legal advice, and a city's reading of a new law can differ in the first months. Ask your planning or building department for its position in writing before you spend money on plans.
January 1, 2027. The Governor signed it on September 29, 2026 as Chapter 780 of the Statutes of 2026. It is an ordinary, non-urgency statute.
From January 1, 2027, no more than two plan check and specification reviews on a building permit application covered by Government Code section 65913.3. After two, the agency may deny an application that is still non-compliant, and more rounds happen only if the applicant asks.
The bill does not mention ADUs by name. It covers building permits issued under the California Building Standards Code, and a stand-alone ADU building permit appears to fit. Ask your building department in writing how it will apply the limit.
From January 1, 2027, for a covered building-permit inspection, the agency may request or require a deviation from a previously approved building plan or similar approval only with written findings based on substantial evidence that one of the statutory exceptions applies.
For housing projects with 25 units or fewer, 30 business days from receiving the written appeal. For projects with 26 units or more, 45 business days. If the appeal is denied or late, the applicant may seek a writ of mandate.