Which route applies to your unit
| Your unit | Route | What it is judged against |
|---|---|---|
| ADU or junior ADU in California, built or converted before 1 Jan 2020 | AB 2533 legalization permit | Life-safety standards in effect when it was built; parts replaced after 2020 meet current code |
| California unit built in 2020 or later | Ordinary permit, as new construction | Current code, plus current ADU zoning rules |
| Any other unpermitted room, garage conversion or guesthouse | Ordinary permit, as new construction | Folsom: "requires compliance with TODAY'S code requirements" |
| Outside California | Your city's rules; some run amnesty programs | Usually current code. Miami has an ADU amnesty program (Miami fee schedule) |
What the California rule says, in the agencies' words
Two local agencies that have published their AB 2533 process, read 22 October 2026:
| Los Angeles County (unincorporated) | City of Hayward | |
|---|---|---|
| Which units | Unpermitted ADUs and JADUs "constructed prior to January 1, 2020" | Units that "must have been built or converted before January 1, 2020", in residential zones |
| Standard | "Minimum life and safety standards" of the County residential code in effect at the confirmed construction date; "Full compliance with current building codes is not required" | Health and Safety Code 17920.3; "Any fire and life safety and Housing Code violations documented at the time of the inspection must be corrected" |
| Who inspects | County inspector; owner may hire a third-party inspector first, at the owner's expense | City inspector, or a third-party inspection by a licensed contractor |
| Proof of date | Inspector verifies on site | Letter from a licensed professional, Assessor records, escrow documents or prior City records |
| Fees | Plan review and inspection fees; extra fees from the third review or inspection; no penalties while seeking legalization | A fee that varies, plus administrative and state fees |
| Time limits | County reviews a complete application in 60 days, resubmittals in 30; owner has two years from permit issue to finish | None stated |
| Junior ADUs | Covered | Owner-occupancy and a recorded deed restriction required |
Note what the rule does not do. It does not waive the work: if the inspector finds a missing smoke alarm, an unsafe heater or a bedroom without a second way out, you fix it under a permit. And components "replaced or modified after January 1, 2020" must meet the current code (LA County).
The ordinary route: legalizing as new work
Where AB 2533 does not apply, legalizing is a normal permit for work that already exists. Folsom's building counter handout sets out the usual approach: "Projects without permits shall be considered new construction", which "requires compliance with TODAY'S code requirements". In practice that can mean opening finished walls so the inspector can see framing, wiring and plumbing. Some cities add a penalty fee: Miami charges work started without a permit "two times that specified in the fee schedule, plus an additional base fee" on homestead property and four times elsewhere (Sec. 10-18), with a separate ADU amnesty program.
What legal ADU permits look like in our cities
For comparison, here are ADUs that went through the permit process from the start:
| City | ADU permits | Usual filed value | Usual days, permit to final | Reached a final |
|---|---|---|---|---|
| San Diego | 1,278 | $127,372 | 442 | 75.1% |
| San Diego County (unincorporated) | 334 | $128,106 | 351 | 85.1% |
| Sacramento County | 207 | $133,039 | 254 | 92.8% |
| Anaheim | 330 | $100,000 | 307 | 94.0% |
| San Francisco | 333 | $169,365 | 567 | 52.5% |
Even permitted-from-day-one ADUs take most of a year or more to reach a final, and in San Francisco only 52.5% of ADU permits a year or more old had one. A legalization permit that needs corrections is a permit like these; it is closed only when the final inspection is recorded.
Check it in five minutes
- Search your address on your city or county's permit portal and see what is on file for the unit. Our did my contractor pull a permit guide has the links for our cities.
- If you are in California, search your city or county's site for "AB 2533" to find its form and checklist.
- Gather proof of the build date: Assessor records, escrow papers, old photos, a letter from a licensed professional.
- If corrections are needed, hire a licensed contractor who has finished ADU permits; check on our compare page, for example San Diego ADU builders.
Compare San Diego ADU builders by finished permits →
What this does not tell you
We read two agencies' AB 2533 pages, not the statute itself, and each local agency publishes its own process and fees. Outside California we know only the rules of the cities we cite. Our permit data covers units that were permitted; it cannot show how many unpermitted ADUs exist or how many were legalized. Selling or renting an unpermitted unit raises disclosure questions; see permit vs no permit. Nothing here is legal advice.
How we know this
The AB 2533 rules are quoted from Los Angeles County Public Works' Administrative Manual AM 80.12 (approved 19 February 2026) and the City of Hayward's AB 2533 page, both read 22 October 2026. The new-construction rule is quoted from Folsom's handout and the penalty from Miami's fee schedule, read 20 October 2026. ADU permit counts, filed values, days to final and finished shares come from the City of San Diego, County of San Diego, Sacramento County, City of Anaheim and San Francisco DBI permit files, three-year windows ending September 2026.
Numbers come from City of San Diego Development Services approvals; Sacramento County building permits on single-family, duplex and townhouse homes in the unincorporated county (the County's Accela permit layer); San Francisco DBI building permits on one- and two-family homes, with the contractor from the city's permit contacts file; City of Anaheim Accela building permits on single-family homes and ADUs; San Diego County Planning & Development Services building permits on homes in the unincorporated county (the County's open-data permit, contractor and status-history files), data through October 17, 2026. Nobody paid to be on this page and nobody can.
Questions
- What if my ADU is not authorized? Can it be made legal?
In California, usually yes if it was built before 1 January 2020. AB 2533 (Gov. Code § 66332, in force since 1 January 2025) bars a local agency from denying a permit to legalize such a unit unless it makes a final determination that the violations cannot be remedied, and from penalising an owner who is seeking legalization (LA County Public Works, Feb 2026). Elsewhere, legalizing usually means meeting today's code.
- What if my guesthouse was already built without a permit?
If it is a dwelling unit in California built before 2020, the AB 2533 route above applies. If not, it is treated like any unpermitted work: you apply for a permit as if it were new, and the inspector judges it against current code. Folsom's handout says such projects 'shall be considered new construction' and must meet 'TODAY'S code requirements'.
- How much does it cost, and how long does it take, to legalize unpermitted work?
Under AB 2533 in unincorporated Los Angeles County, you pay the plan review and inspection fees (more after a second review) but no penalties; the County has 60 days to review a complete application and you have two years from permit issue to finish the corrections. Outside that route, cities charge more: Miami bills work started without a permit at two times the fee on a homestead and four times elsewhere, plus a base fee.
- What do inspectors check on an unpermitted ADU?
Life and safety, not the full current code. LA County measures the unit against the minimum life and safety standards of its residential code in effect when the unit was built; Hayward inspects against Health and Safety Code 17920.3 and requires fire, life safety and housing code violations to be corrected. Anything replaced after 1 January 2020 must meet current code.
- How do I prove when my ADU was built?
Hayward accepts a letter from a licensed professional, Assessor records, escrow documents or prior City records. In LA County, the inspector verifies the pre-2020 construction on site, and a disagreement over the date sends the file back for review.
- How long does a legal ADU permit take to close?
In our California cities the usual ADU permit went from issue to final in 254 days in Sacramento County, 442 in San Diego and 567 in San Francisco.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- What is an ADU? ADU vs DADU vs JADU, California's rules, and what ADU permits show
- ADU vs home addition: what the permit file shows
- How to check a contractor's license in California
- ADU cost in San Diego County: what the permits were filed at, by size
For one city
- AM 80.12 AB 2533: Permitting Unpermitted ADUs and JADUs Built Before January 1, 2020 — Los Angeles County Public Works, Building and Safety (approved 19 Feb 2026) (accessed 2026-10-22)
- Assembly Bill 2533, ADU Amnesty program — City of Hayward (accessed 2026-10-22)
- Legalizing an existing room addition (City of Folsom Building Counter handout, 2014) (accessed 2026-10-20)
- City of Miami Building Permit Fee Schedule (Sec. 10-18) (accessed 2026-10-20)