California AB 253 is enacted law. Effective October 10, 2025, it allows an applicant for certain 1-to-10-unit, residential-only projects to retain a qualified private professional provider at the applicant's expense when the city or county estimates more than 30 business days for plan check—or has not determined compliance within 30 business days after the application is deemed complete. The law establishes notice, qualification, affidavit, report, and local-agency response requirements; it does not let any architect, engineer, or AI tool independently issue a permit. Groundbook AI is not the private professional provider the law describes. It is the AI review tool that a qualified provider, an applicant's design team, or a building department can use to get through the plan check the law puts on a 30-business-day clock.
Where Groundbook AI stands on AB 253
Readers ask us whether Groundbook AI “is” an AB 253 reviewer, competes with building departments, or takes a side on the law. The short answers:
- We are a tool, not the provider. Groundbook AI is not a California-licensed architect or engineer, holds no plans-examiner certification, cannot sign the affidavit under penalty of perjury, and cannot issue or “deem approved” a permit. The statutory role belongs to a qualified human provider.
- We are the first pass the provider runs. A qualified private professional provider uses Groundbook AI to screen the complete permit set against the code, local amendments, and the jurisdiction's checklist, with every finding linked to the sheet and the source. The provider decides what complies and signs the statutory documents.
- We serve every side of the process, not one side against another. Applicants and design teams use it to submit a cleaner set. Private providers use it to deliver the AB 253 review. Building departments can use it to bring their own plan check under 30 business days, so the private path is never triggered.
- On the policy itself: we think faster, better-documented residential plan review is good for housing, whether it happens at the counter or through a private provider. AB 253 sets the clock; our job is to help public and private reviewers meet it with the evidence trail the statute expects.
We do not guarantee permit timing or approval, and nothing on this page is legal advice.
Use Groundbook AI to move AB 253 plan review faster
Qualified private professional providers can use Groundbook AI to screen the complete permit set, cross-check code and project requirements, and investigate traceable findings before preparing the statutory affidavit and report—helping the plan-check and permitting workflow move faster without changing who makes the legal determination.
AB 253 is enacted law—not a pending proposal
Assembly Bill 253, the California Residential Private Permitting Review Act, was approved by the Governor and chaptered as Chapter 487 of the Statutes of 2025 on October 10, 2025. Because it was enacted as an urgency statute, it took effect that day. The private-review provisions in Health and Safety Code Section 17960.3 remain in effect only until January 1, 2036.
The official sources are the chaptered AB 253 text, the Legislature's bill status and history, and the Governor's October 10, 2025 signing announcement.
This guide summarizes the enacted text for general information. It is not legal advice, and applicants and reviewers should confirm the current process with the city or county and qualified California counsel.
When may an applicant use a private plan reviewer?
The clock does not start when an applicant first contacts the building department. It starts when the residential building-permit application is deemed complete under Government Code Section 65913.3. From there, AB 253 creates two paths:
- The city's or county's estimate exceeds 30 business days. When the complete application is acknowledged, the jurisdiction must provide an estimated timeframe for determining whether it complies with permit standards. If that estimate is longer than 30 business days, the applicant may retain a private professional provider.
- No compliance determination arrives within 30 business days. Even if the original estimate was shorter, the applicant may retain a provider if the jurisdiction has not determined compliance within 30 business days after the application was deemed complete.
The applicant pays for the private review and must notify the city or county of the intent to retain a provider no later than five business days after receiving the over-30-day estimate or after the 30-business-day period expires. That notice deadline is an important part of the statutory process.
Common shorthand to avoid: AB 253 is not a general right to bypass a building department after 30 calendar days. The statute uses business days, a complete application, specific notice timing, and defined project and reviewer qualifications.
Which residential projects qualify?
AB 253 defines an eligible “residential building permit” narrowly. It covers either:
- New residential construction containing at least 1 and no more than 10 dwelling units, containing only residential units, with no floor used for human occupancy more than 40 feet above ground level; or
- An addition to or remodel of an existing residential-only building with 1 to 10 units, when the work adds residential units and the completed building will have no more than 10 units, subject to the same occupied-floor height limit.
The enacted text does not describe eligibility simply as “four stories or fewer.” The controlling test is whether any floor used for human occupancy is more than 40 feet above ground level. It also requires a residential-only building, so a mixed-use building with commercial space does not fit this definition.
Who qualifies as a private professional provider?
A provider must satisfy both professional-licensing and plans-examiner certification requirements. Under AB 253, the provider must be:
- A professional engineer licensed under California's Professional Engineers Act or an architect licensed under California's Architects Practice Act; and
- Currently certified as a residential plans examiner by the International Code Council, currently certified as a plans examiner by the International Association of Plumbing and Mechanical Officials, or currently certified by another state, national, or international association the local agency accepts for its own residential plans examiners.
The provider must not have a financial interest in the residential building permit or in preparing the project's plans and specifications. A professional license by itself is therefore not enough, and the project's designer does not automatically qualify to perform the independent statutory review.
What happens after the private plan check?
The private provider checks the plans and specifications for compliance with the State Housing Law requirements and applicable local ordinances. AB 253 does not provide a separate discipline-by-discipline scope; the governing state and local requirements define the review.
The provider must prepare an affidavit under penalty of perjury stating whether the plans and specifications comply and confirming that the provider performed the plan check. The applicant submits a report to the city or county containing:
- The provider's affidavit;
- The changes necessary for compliance if the provider finds that the plans do not comply; and
- Any additional information required by the city or county.
Within 10 business days after receiving the report, the city or county must either issue the residential building permit when the plans comply or provide written notice identifying the remaining noncompliance and what must be remedied. If the jurisdiction does neither within that period and the provider's affidavit states that the plans comply, the statute says the plans are deemed compliant and the permit is deemed approved.
The applicant must indemnify the local agency from property damage or personal injury arising from construction performed under plans checked through this process. Corrected plans may be resubmitted when the jurisdiction identifies noncompliance.
What cities and counties must publish or report
AB 253 also changes local-agency transparency and reporting:
- A city or county that charges residential building-permit fees must prepare a fee schedule and post it on its website. This requirement appears in the current Health and Safety Code Section 17951.
- After a residential permit application is deemed complete, the jurisdiction must give the applicant an estimated timeframe for its compliance determination.
- Beginning April 1, 2027, jurisdictions must include private-review counts, local-review counts, and related staffing information in specified annual reports.
Local application instructions, required report formats, accepted examiner certifications, and submission portals may differ. Applicants should use the jurisdiction's current published procedure rather than treating a general summary as a filing checklist.
Groundbook AI's role under AB 253: what it does and does not do
AB 253 creates a legal role for a qualified human private professional provider. An AI plan-review product is not a California-licensed engineer or architect, cannot satisfy the statutory certification requirements, cannot sign the affidavit under penalty of perjury, and cannot issue a building permit.
Groundbook AI can help the qualified provider move faster through the review work that comes before the statutory affidavit and report. Instead of manually opening every drawing, specification, checklist, and code source one at a time, the reviewer can run a traceable first pass across the complete document set and investigate possible coordination and compliance issues from the cited file, page, and drawing location.
- Screen the complete permit set sooner: cross-check architectural, structural, MEP, fire-protection, and civil documents in one review.
- Apply the sources selected for the project: include specifications and jurisdiction checklists, plus the adopted code and local amendments. Groundbook reads the codes and amendments that governments publish online and uses licensed model codes only where a license allows it; you can upload a copy you're licensed to use.
- Start professional review from traceable findings: give the licensed reviewer the issue, supporting evidence, and exact source location instead of an unstructured AI response.
That faster, more organized first pass can help an AB 253 plan check—and the path to a permit—move faster. The qualified provider still decides what complies, prepares and signs the statutory documents, and retains professional responsibility; the city or county retains its role under the enacted process. Groundbook AI does not guarantee permit timing or approval.
How cities are implementing AB 253
The statute sets the framework; each city and county decides the forms, fees, and disciplines. Two published examples show how different the local procedure can look:
- San Diego runs AB 253 through its Development Services Department program. Eligibility is triggered when none of the review disciplines has commented or signed off within 30 business days; the applicant then emails a completed Form DS-253A within five business days. The private plan check covers the city's listed disciplines—structural, mechanical, electrical, energy, plumbing, gas, accessibility, life safety, fire suppression and alarm, and hazardous materials—against State Housing Law and the city's California Building Code amendments. The applicant submits the private plan check report with the affidavit and an indemnification agreement, processing fees are added from the city's Express fee schedule, and the department reviews the report within 10 business days. Inspections stay with the city.
- Sonoma County has had its own third-party plan check program since before AB 253. The applicant picks a consultant from the county's approved list and pays the consultant directly, the county's building plan check fee is reduced by 25 percent, the county continues reviewing other disciplines such as grading and septic in parallel, and the county keeps final approval. That program is a local option with its own rules, not the statutory AB 253 path, and its instructions do not mention AB 253.
Before relying on either the statutory path or a local program, get the jurisdiction's current instructions in writing. Which one applies, what the reviewer must cover, and what the applicant pays differ by city.
A practical AB 253 preparation checklist
- Confirm that the project fits the statute's unit, residential-only, work-type, and occupied-floor-height limits.
- Obtain and retain the jurisdiction's written determination that the application is complete.
- Record the estimated review timeframe and the date the 30-business-day period begins.
- Identify a California-licensed architect or engineer with a plans-examiner certification the local agency accepts.
- Check independence and financial-interest restrictions before retaining the provider.
- Send the required notice to the city or county within the applicable five-business-day window.
- Confirm the jurisdiction's report format, required additional information, local amendments, fee schedule, and submission method.
- Keep the affidavit, report, corrections, delivery records, and every response from the jurisdiction in one permit file.
Because deadlines and deemed-approval consequences can be legally significant, applicants should coordinate the actual filing with the jurisdiction and qualified counsel.