How Do You Legalize an Unpermitted ADU or Garage Conversion in California Under AB 2533?

Published July 15, 2026

AB 2533, effective January 2025, blocks cities from denying permits on unpermitted ADUs built before 2020.

AB 2533, effective January 1, 2025, lets you legalize an unpermitted ADU or JADU built before January 1, 2020. A city cannot deny the permit just because the unit misses current building or ADU code. It can only require fixes needed to clear health and safety thresholds under Health and Safety Code section 17920.3. Impact and connection fees are barred except in narrow cases, and you have a right to a confidential inspection first.

What AB 2533 actually changed

California already had a rule protecting old unpermitted ADUs. SB 897, signed in September 2022 and effective January 1, 2023, said a city could not deny a permit to legalize an unpermitted accessory dwelling unit built before January 1, 2018, unless correcting the violation was necessary to protect health and safety. AB 2533, authored by Assemblymember Juan Carrillo and signed as Chapter 834 of the 2024 statutes, moved that cutoff forward. Now the protected date is any unit built before January 1, 2020. That two year shift pulls a lot more South Bay garage conversions and back house units into the amnesty.

One housekeeping note that trips people up. The core ADU statute used to live at Government Code section 65852.2. In early 2024, a separate bill, SB 477, renumbered the ADU laws into a new chapter, so the current home for these rules is Government Code section 66332. If you see the old section cited, it is the same body of law under a new number.

The protection, in plain terms

Under Government Code section 66332, a local agency cannot deny a permit to legalize a qualifying pre 2020 ADU or junior ADU solely because it fails to meet current ADU standards or building code. The only violations a city can force you to correct are the ones that rise to the level of a substandard building under Health and Safety Code section 17920.3. That statute covers real hazards. Think faulty wiring, inadequate sanitation, structural danger, not a setback that is a foot short or a ceiling an inch low.

The law also limits money. Impact fees, connection fees, and capacity charges generally cannot be imposed on the legalization, with only narrow exceptions. And cities must publish a checklist of the health and safety items they will review, plus a notice telling you that you have the right to a confidential third party inspection before you ever file.

The confidential inspection is your friend

That pre application inspection matters. It lets you learn what a city will flag before you put your name on a permit application, so there are no surprises. If the inspector finds deficiencies, the agency has to approve the corrective permits and cannot penalize you for the fact that the unit went up without a permit in the first place.

How an owner actually does this

The path is straightforward, even if the paperwork takes patience.

1. Confirm the unit was built before January 1, 2020 and meets the ADU or JADU definition in Government Code section 66332. Photos, old utility bills, or aerial imagery can help date it.
2. Use your right to a confidential inspection to scope the work first.
3. Apply to your local building department using the section 17920.3 checklist the city is required to publish.
4. The inspector reviews health and safety items only, not full modern code.
5. Correct any genuine hazards, pull the corrective permits, and get your certificate.

South Bay cities are standing this up. Redondo Beach, for example, already runs an AB 2533 legalization program with its own application and substandard housing checklist. Others are following, since the statute requires every agency to publish the information.

What this means for you

If you own a South Bay property with a garage conversion or back unit that was never permitted and predates 2020, this law tilts strongly in your favor. Legalizing turns a liability into a rentable, insurable, financeable asset. The city cannot hold your old code gaps against you. It can only make you fix true safety problems. Start with the confidential inspection so you walk in knowing the scope.

We walk owners through exactly this, from dating the unit to lining up the corrective permits. If you have a unit you have been afraid to touch, we can tell you where you stand before you commit to anything.

This is general information, not legal or tax advice. Confirm with a licensed professional before you act.

Sources

1. AB 2533 (2024), Chapter 834, official bill page: https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202320240AB2533
2. California HCD, Accessory Dwelling Units page (handbook and guidance): https://www.hcd.ca.gov/policy-and-research/accessory-dwelling-units
3. Health and Safety Code section 17920.3 (substandard building definition): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=17920.3&lawCode=HSC
4. Government Code section 66332 (accessory dwelling units, current codification): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=66332&lawCode=GOV
5. City of Redondo Beach, AB 2533 ADU Legalization program: https://www.redondo.org/departments/community_development/building_and_safety/assembly_bill_2533_(adu_legalization).php

Last verified: July 2026.

Topics: compliance, adu, ab 2533, garage conversion, permits, california housing law

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