Unpermitted ADU in California: how to legalize it under AB 2533

Unpermitted ADU California law

The rule is Government Code section 66311.7, which AB 2533 rewrote in 2024. It has six parts.

In practice, that means a pre-2020 ADU that's too big, too close to the property line, or missing the parking a city once required can be permitted as it stands. What has to change are things like missing smoke alarms, unsafe wiring or a bedroom with no way out in a fire. For the rest of state ADU law, see California ADU laws.

Which units qualify

Two tests decide whether section 66311.7 helps you.

• It was built before January 1, 2020. You'll have to prove it. The City of San Diego accepts documents like contractor bills, utility or insurance records, code enforcement records, signed leases, real estate documents and dated photographs.
• It's actually an ADU or JADU. Under state law, an ADU is a unit with complete, independent living facilities: permanent provisions for living, sleeping, eating, cooking and sanitation. A converted room without a kitchen isn't one. A JADU is up to 500 square feet of interior livable space inside a single-family home. If you're unsure, start with what an ADU is.

The unit can be detached, attached or a conversion of existing space. A unit built in 2020 or later doesn't get this protection; it goes through a regular ADU permit and has to meet today's rules. Most of those rules are generous anyway, as our San Diego ADU permit guide explains.

What AB 2533 changed

The ban on denying permits for unpermitted ADUs began with legislation that took effect in 2023. According to HCD's ADU handbook, that version covered units built before January 1, 2018. AB 2533 (Chapter 834, Statutes of 2024) took effect January 1, 2025, and widened it.

The confidential inspection matters. You can hire a licensed contractor to look at the unit and estimate the work privately, before you apply. If the scope is bigger than you expected, you haven't started anything. Before you hire one, check a contractor's license.

What still has to be fixed

The exception that remains is health and safety, defined by Health and Safety Code section 17920.3, the state's list of conditions that make a building substandard. The City of San Diego turned that list into a checklist, Attachment A of Information Bulletin 242, and says any item that doesn't comply must be corrected as part of the permit.

Work done after January 1, 2020, is treated differently. The city checks later work, including heating equipment, electrical equipment and water heaters, against current codes. The state handbook adds that building code and health and safety corrections are within the city's discretion, and that you should use the city's appeal process if you disagree with a correction or denial. For the code a new ADU must meet, see our ADU building code guide.

How to legalize an unpermitted ADU in San Diego

The City of San Diego's process is in Information Bulletin 242, updated May 2026. You apply for a building permit online and note in the scope of work that the project uses AB 2533. The application needs:

• Proof of the construction date, shown on the plans and backed by documents.
• A site plan with property lines, the unit's location, setbacks, lot coverage, easements, utility connections and fire access.
• A floor plan showing rooms, cooking appliances, toilet and sink, water heater, heating, smoke and CO alarms, exit doors, escape windows and GFCI outlets where required.
• Attachment A, the substandard-conditions checklist.
• The code enforcement case number, if you're applying because of a Building and Land Use Enforcement notice.

After the permit is issued, inspectors confirm the unit isn't substandard. Fees work like this under the bulletin:

The water meter isn't resized as part of the review, though the billing rate code may change.

Units the bulletin doesn't cover

• Unpermitted work in areas subject to the Coastal Act, which follows the city's coastal development rules instead. See our ADU coastal zone guide.
• Units the bulletin flags as ineligible for the streamlined path or needing extra documentation: those in a fault, landslide or liquefaction area, created by digging out under the floor, built with materials the building code doesn't allow, sitting on an easement, or attached to an apartment or commercial building.

Outside those streamlined criteria, the city may require architectural and structural plans, calculations or a soils report. Other cities in the county run their own process under the same state law; ask their building department for the section 66311.7 checklist they're required to publish.

Unpermitted garage conversions

Garage conversions are the most common unpermitted unit, and whether the law helps depends on what's inside.

• A full unit with a kitchen and bathroom, built before 2020, can qualify as an unpermitted ADU under section 66311.7. State law also says a city can't require you to replace the lost parking when a garage is converted to an ADU, according to HCD's handbook.
• A bedroom, office or gym with no kitchen isn't an ADU, so this protection doesn't apply. It needs an ordinary permit for the work, under current code.
• A conversion done in 2020 or later needs a regular permit either way.

If the space is close to a full unit, it can be worth finishing it as a permitted ADU. Our garage conversion ADU guide covers the upgrades a garage typically needs.

Selling a home with an unpermitted ADU

California sellers fill out a Real Estate Transfer Disclosure Statement, and the form asks the seller directly about three things that cover most unpermitted ADUs:

• Room additions, structural modifications, or other alterations or repairs made without necessary permits.
• Room additions, structural modifications, or other alterations or repairs not in compliance with building codes.
• Zoning violations, nonconforming uses and setback violations.

The form states that these are the seller's representations, not the agent's. If you know the unit wasn't permitted, the form asks you to say so.

Flips face an extra rule. For a single-family home where the seller accepts an offer within 18 months of taking title, and on or after July 1, 2024, Civil Code section 1102.6h requires the seller to disclose additions, alterations and repairs done by a contractor the seller hired, name the contractor, and hand over copies of any permits obtained.

A permitted unit is one less problem to disclose. For how ADUs affect a sale and appraisal, see our ADU real estate guide.

Legalize, delay or remove

The delay option comes from Health and Safety Code section 17980.12. If you get a notice to correct violations at an ADU built before 2020, you can apply to delay enforcement for five years, and the agency must grant it if correcting the violation isn't necessary to protect health and safety. The notice itself has to tell you about this right. It buys time; it doesn't legalize the unit.

Leaving the unit as is carries the risks above: a code enforcement notice, a disclosure on sale, and tenants living with conditions no one has inspected. If you decide to legalize or rebuild, read how to hire an ADU contractor, check what an ADU costs in San Diego if a rebuild is on the table, or compare verified ADU builders in San Diego.

Common questions