California • Unpermitted ADU legalization
How to Legalize an Unpermitted ADU in California Under AB 2533
If an ADU or JADU was built before January 1, 2020, California law can limit the reasons a city or county may deny legalization. The protection is meaningful—but it is not blanket amnesty. Health-and-safety conditions can still require correction.
The quick answer
AB 2533 created a legalization path for qualifying unpermitted ADUs and JADUs constructed before January 1, 2020. A local agency generally cannot deny the permit merely because the unit violates building standards or current ADU/JADU rules. The agency may still require corrections when needed to address conditions that would make the building substandard under Health and Safety Code § 17920.3.
The operative rule is now Government Code § 66311.7. Older material may refer to former § 66332.
60-second screen
Does your unit appear to fit the AB 2533 pathway?
1. Was it constructed before January 1, 2020?
If no, this specific protection does not apply. If yes or uncertain, gather evidence that can help establish when the unit was created.
2. Is it actually an ADU or JADU?
Document the unit’s living, sleeping, cooking and sanitation facilities and how it relates to the primary residence.
3. Are there obvious health or safety concerns?
Serious structural, sanitation, wiring, plumbing, fire, exit, weatherproofing or similar conditions may need correction before approval.
4. Can you identify the permitting jurisdiction?
The responsible city or county should publish AB 2533 information and a checklist of substandard-building conditions.
What the law does
What AB 2533 protects—and what it does not
| Issue | State-law protection | What may still happen |
|---|---|---|
| Old building-code violations | A qualifying pre-2020 unit generally cannot be denied solely for those violations. | Corrections may still be required if necessary to address a condition that would make the building substandard. |
| Noncompliance with current ADU/JADU rules | A qualifying unit generally cannot be denied solely because it does not comply with current state or local ADU/JADU standards. | The agency can still inspect for health-and-safety conditions. |
| Impact fees | The homeowner generally cannot be required to pay impact fees for the qualifying legalization application. | Other project costs may remain. |
| Connection or capacity charges | Generally protected from these charges. | An exception can apply when utility infrastructure is required to address § 17920.3 conditions and the charge is otherwise authorized by law. |
| Penalties for having the unpermitted unit | If an inspector finds health-and-safety noncompliance, the local agency cannot penalize the applicant merely for having the unpermitted ADU/JADU. | The agency may issue the permits needed to correct the unsafe condition. |
Important: AB 2533 is a legalization protection, not a promise that every old conversion can remain exactly as built.
Safety screen
What conditions can still trigger corrections?
Health and Safety Code § 17920.3 defines conditions that can make a building substandard when they endanger occupants or the public. The statute includes, among other things:
Sanitation and habitability
- Improper or missing plumbing fixtures
- Lack of hot and cold running water
- Inadequate heating or ventilation
- Dampness or visible mold
- Lack of sewage disposal
Structure and weather protection
- Inadequate or deteriorated foundations
- Unsafe floors, walls, ceilings or roofs
- Failed waterproofing or exterior protection
- Unsafe structural resistance
Electrical, plumbing and mechanical
- Unsafe wiring
- Unsafe plumbing
- Unsafe mechanical equipment or vents
Fire and exiting
- Inadequate exit facilities
- Missing required fire-resistive construction or systems
- Conditions creating a fire or explosion hazard
Read the current Health and Safety Code § 17920.3 and use your local agency’s required checklist rather than treating this summary as an inspection.
Before you apply
Build a legalization evidence file first
The statute does not prescribe one universal proof packet for the construction date. Build a practical file that helps the local agency understand what exists and when it was created.
Optional risk-reduction step
Consider the confidential third-party inspection before filing
Government Code § 66311.7 requires local agencies to tell homeowners that, before submitting the permit application, they may obtain a confidential third-party code inspection from a licensed contractor to understand the unit’s existing condition and potential scope of improvements.
Application workflow
A practical AB 2533 legalization sequence
Confirm jurisdiction
Identify the city or county that actually issues permits for the parcel and find its AB 2533 legalization page/checklist.
Document the unit and construction date
Assemble the evidence file before anyone redraws or demolishes existing conditions.
Review the § 17920.3 safety checklist
Flag obvious sanitation, structure, electrical, plumbing, weatherproofing, fire or exit concerns.
Decide whether to obtain the confidential inspection
Use it to estimate the likely correction scope before submitting.
Ask the agency targeted questions
Confirm required drawings, evidence of age, inspection sequence, fee treatment and any local forms.
Submit and preserve the record
Keep the application, correction notices, inspection reports, approved plans and final approval together with the property file.
Take these to the counter
Questions to ask your city or county
- What evidence will you accept to show the ADU/JADU was constructed before January 1, 2020?
- Where is your AB 2533 / § 66311.7 public checklist?
- Which § 17920.3 conditions will your inspector evaluate?
- What plans or measured drawings are required for legalization?
- Which fees are waived, and which fees can still apply?
- If utility work is required for health and safety, what written basis supports any connection or capacity charge?
- What is the inspection and correction sequence?
- What document proves final legalization when the work is complete?
Official sources
Verify the current rule before you file
- California Government Code § 66311.7 — previously unpermitted ADUs/JADUs
- California Health and Safety Code § 17920.3 — substandard-building conditions
- California HCD — ADU Handbook, updated March 2026
Independent educational resource: ADU Project Planner is not a permitting agency, attorney, architect, engineer or contractor. This page organizes the state-law pathway for homeowner planning; the responsible local agency determines the project-specific permit and correction process.
Continue planning