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Unpermitted ADU legalization in California

By the HyreADU research desk. Last checked .

The short answer

Unpermitted ADU legalization in California rests on Gov. Code § 66311.7. A city may not deny a permit for an unpermitted ADU built before 1 January 2020 just because it breaks building standards or local ADU rules.

The exception is health and safety under Health & Safety Code § 17920.3. Impact fees and connection charges are waived.

What the state route gives you

Denial is allowed only where fixing the problem is needed to meet the substandard-building test in § 17920.3.

The applicant does not pay impact fees or connection or capacity charges, unless utility work is needed to fix such a condition.

And the city may not penalize you for having had the unit. See legalizing an unpermitted ADU.

Who helps with legalization

A designer or architect draws the unit as it is. An inspector or contractor opens walls where the city needs to see framing, wiring or plumbing. A permit expediter can help with a city that has its own amnesty program. Local programs may have deadlines the state route does not.

Before you start

Find out when the unit was built, with records if you can. Ask your city for its legalization page and checklist. If the unit is rented, get legal advice on tenant rights first. HyreADU gives no legal advice.

What to do next: read the questions to ask an ADU builder, check what decides ADU cost, then tell us about your project. Matching is not live yet, so we reply with information, not a quote.

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Questions

What if my unit was built after 2020?

The state route does not cover it. It must meet current rules or be permitted as a new ADU.

Will the city fine me for coming forward?

Under § 66311.7 the city may not penalize you for having the unpermitted unit.

Do I have to bring it fully up to code?

Not for building standards alone, but health and safety issues must be fixed.

How many unpermitted ADUs are there?

See our estimate in how many unpermitted ADUs.

Sources

HyreADU is a publisher. It does not design, permit or build ADUs, has no partner builders, and gives no legal, tax or engineering advice. Rules vary by state and city; California rules are labeled as such.