How to Legalize an Unpermitted ADU in California (AB 2533)

If your ADU or JADU was built without permits before January 1, 2020, California law gives you a clear path to legalize it. Under AB 2533, effective January 1, 2025, a city can't deny the permit because of building code violations unless the unit is substandard under Health and Safety Code §17920.3, meaning it's a real health and safety hazard. The city also can't make you fix nonconforming zoning conditions or charge fees for the unpermitted construction itself.

Key takeaways

• ›AB 2533 covers ADUs and JADUs built before January 1, 2020. The earlier law only covered units built before 2018.
• ›A city can deny legalization for code violations only if the unit is substandard under Health and Safety Code §17920.3.
• ›Cities can't require you to correct nonconforming zoning conditions, and impact and connection fees are limited.
• ›You can request an inspection confidentially, and the city must tell you what needs fixing.

What does AB 2533 change for unpermitted ADUs?

AB 2533 (2024) expanded California's earlier ADU amnesty in several ways:

• ›Later cutoff date. The earlier rule covered units built before 2018. AB 2533 covers ADUs and JADUs built before January 1, 2020.
• ›Health and safety is the only code-based reason to deny. A city can't deny a permit to legalize the unit for building code violations unless the unit is substandard under Health and Safety Code §17920.3. That section covers conditions like inadequate sanitation, structural hazards, faulty wiring or plumbing, and fire hazards.
• ›No zoning fixes. The city can't require you to correct nonconforming zoning conditions, such as a unit that sits closer to a property line than current rules allow.
• ›Limited fees. Impact fees and connection fees are limited, and the city can't impose fees for the unpermitted construction itself. You still pay normal permit and inspection fees.
• ›Confidential inspection. You can request an inspection confidentially to learn what the unit needs.
• ›A clear list. The city must tell you what needs fixing, so you aren't guessing.

In short, the question shifts from "does this unit meet today's code?" to "is this unit safe?"

Does my unit qualify?

Check three things:

1. ›Build date. You need evidence the unit existed before January 1, 2020. Useful records include dated photos, utility bills, old leases, tax records, aerial imagery, insurance records, or contractor invoices.
2. ›Unit type. AB 2533 covers ADUs and JADUs. A garage converted to living space, a backyard cottage, or a unit inside the main home can all qualify.
3. ›Condition. If the unit has serious hazards under §17920.3, you'll have to correct those before the city signs off.

If the unit was built in 2020 or later, AB 2533 doesn't apply. You'd follow the normal ADU permit process for new work, and the city can require the unit to meet current code.

How do you legalize an unpermitted ADU step by step?

1. ›Gather records. Collect proof of the build date, any old plans, and a list of the work done (electrical, plumbing, gas, structural). The more you document, the fewer surprises later.
2. ›Get a pre-inspection from a private inspector. A licensed home inspector or contractor can walk the unit and flag likely §17920.3 issues, such as missing smoke alarms, unsafe wiring, no hot water, or inadequate egress. This tells you what to fix before the city sees it.
3. ›Submit the application. Most cities want as-built plans (drawings of the unit as it exists), a site plan, and the application form. Ask for the city's AB 2533 or legalization checklist.
4. ›City inspection. An inspector visits and identifies what must be corrected. Under AB 2533, the city must tell you what needs fixing.
5. ›Make corrections. Fix the listed items, pulling any trade permits the city requires. Focus is on health and safety, not on bringing the whole unit up to the current code.
6. ›Final inspection. Once corrections pass, the city finalizes the permit. Keep a copy of the permit and final sign-off for your records, your insurer, and any future buyer.

How much does it cost to legalize an ADU?

It varies widely, and we don't have reliable statewide averages. What you'll pay depends on:

• ›As-built plans, prepared by a designer or architect.
• ›Permit and plan check fees set by your city.
• ›Corrections, which can range from a few smoke alarms to new electrical or plumbing work.
• ›Utility work, if a separate connection is needed.

AB 2533 limits impact and connection fees and bars fees for the unpermitted construction itself, which removes some of the biggest cost risks owners used to face. Use the permit fee estimator for a city-by-city starting point.

Example: legalizing a garage conversion in Oakland

Say you own a home in Oakland with a garage that a previous owner converted into a 450 sq ft studio in 2016, without permits. Oakland runs a program to legalize unpermitted ADUs under AB 2533, according to our city data.

Because the unit was built before January 1, 2020, it qualifies. Because it's under 750 sq ft, it owes no impact fees under state law. Based on our Oakland data as of 2026, standard ADU permit fees there run $5,000–$22,000; a legalization's fees depend on scope, so confirm with the city.

A private pre-inspection finds two issues: no smoke or carbon monoxide alarms and an ungrounded circuit. Both are safety items, so you fix them before submitting. The garage sits 2 ft from the side property line, which wouldn't meet some zoning rules today, but AB 2533 bars the city from requiring you to correct that nonconforming condition.

Once legal, the studio can be rented openly. Based on our Oakland data as of 2026, ADUs there rent for roughly $2,000–$5,000 a month.

Do Los Angeles and San Diego have AB 2533 programs?

Yes. Both Los Angeles and San Diego have published local bulletins on legalizing unpermitted ADUs under AB 2533. Our city pages link to each city's official ADU department. Other cities, including San Jose, Sacramento, and Long Beach, apply AB 2533 as state law even without a special program, so ask the permit counter how they handle legalization.

What are the risks of leaving an ADU unpermitted?

Leaving the unit as it is carries real exposure:

• ›Insurance. Your homeowner's policy may not cover damage or liability tied to unpermitted work. A fire that starts in the unit could lead to a denied claim.
• ›Rent. Rent collected on an unpermitted unit may be challenged, and tenants may have claims against you depending on local law.
• ›Enforcement. A complaint or a sale can bring code enforcement, often on the city's timeline instead of yours.
• ›Resale. Buyers, lenders, and appraisers may discount or disregard an unpermitted unit.

Legalizing turns the unit into an asset you can insure, rent, and sell openly. If you plan to rent, read our guide to ADU rental income and run numbers in the ROI calculator. For the full set of state rules, see California ADU laws.

Sources

• ›AB 2533 (2024): legalization of unpermitted ADUs and JADUs
• ›Health and Safety Code §17920.3: substandard buildings
• ›California Government Code §66324: ADU impact fees
• ›HCD: Accessory Dwelling Units
• ›Oakland fee and rent figures: ADUByCity city data for Oakland, as of 2026