# Legalizing an unpermitted ADU built before 2020

> If a unit on your property was built without permits before 2020, state law narrows the reasons a city can refuse to permit it now. The protection is real, and it has an edge you need to know about.

Source: https://www.lotlinepermits.com/california/laws/unpermitted-adu-rules/
Publisher: Lotline
Last reviewed: 2026-11-10

## Key points

- A city can't refuse a permit for a pre-2020 unpermitted unit just because it breaks building standards or ADU rules. [1]
- It can refuse where a correction is needed to meet substandard-building standards. [1]
- Impact fees and connection charges are largely waived. [1]

## Which units qualify

The rule covers an unpermitted ADU or junior ADU that was constructed before January 1, 2020. [1] The date is about when the unit was built, so evidence of age is the first thing to gather: old photographs, utility bills, a lease, an assessor's record or aerial imagery showing the structure in place.

## What the city can't use against you

For a qualifying unit, the local agency may not deny the permit on either of two grounds: that the unit violates building standards, or that it doesn't comply with the state ADU rules or a local ADU ordinance. [1] So a garage unit sitting two feet from a fence isn't refused simply for missing the setback.

## The edge of the protection

The city keeps one ground for refusal. It may deny the permit if it finds that correcting the violation is necessary to comply with the standards in Health and Safety Code Section 17920.3, which is the state's definition of a substandard building. [1]

> **Note:** In plain terms, the law forgives rule-breaking and doesn't forgive danger. Expect an inspector to focus on matters such as wiring, heating, plumbing, structural soundness and fire safety, and expect to pay for those repairs.

## Find out before you apply

Many owners hold back because they fear that asking the question invites enforcement. The statute speaks to that directly. Cities are required to tell the public that, before applying, a homeowner may obtain a confidential third-party code inspection from a licensed contractor to learn the unit's condition and the likely scope of work. [1]

> **Tip:** Doing this first gives you a repair list and a rough budget while the decision to apply is still yours.

## After you apply

Once an application is in, a city inspector may inspect the unit and recommend what is needed to meet health and safety standards. If problems are found, the agency must not penalize you for having had the unpermitted unit, and it must approve the permits needed to correct them. [1]

## Fees

A homeowner permitting a qualifying unit is not required to pay impact fees or connection or capacity charges. The exception is narrow: where utility infrastructure is required for health and safety compliance and the charge is one the fee section permits. [1]

Permit and plan check fees are a different matter and still apply.

## A note on section numbers

These rules were in Section 66332 until SB 543 moved them to Section 66311.7 at the start of 2026. [1] City handouts that mention "66332" are describing the same protection.

## Frequently asked questions

### Does it matter when my unpermitted unit was built?

Yes. The protection applies to units constructed before January 1, 2020. [1] Older guides cite Section 66332 for this; the rules now sit in Section 66311.7. [1] The renumbering is listed under [sections that moved](https://www.lotlinepermits.com/california/laws/sb-543/#sections-that-moved).

### Can I find out what is wrong with the unit before telling the city?

Yes. The statute provides that a homeowner may obtain a confidential third-party code inspection from a licensed contractor before applying. [1]

### Will I be penalized for applying?

If an inspection after you apply finds health and safety problems, the agency must not penalize you for having had the unpermitted unit, and it must approve the permits needed to correct them. [1] Impact fees are largely waived too, as explained on the [impact fees page](https://www.lotlinepermits.com/california/laws/adu-impact-fees/#what-isnt-an-impact-fee).

## References

1. California Government Code, Title 7, Division 1, Chapter 13, Article 1 (Sections 66310 to 66313.5). California Legislative Information. https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=GOV&division=1.&title=7.&part=&chapter=13.&article=1. (read 2026-11-10)

General information only, not legal advice. See https://www.lotlinepermits.com/disclaimer/