April 2025
Number 15

Effective January 1, 2025, Government Code section 66323 (Section 66323) was updated to forbid local agencies from imposing any objective development or design standards unless explicitly authorized in Section 66323, leaving public agencies at a loss for what authority they truly have in the process of reviewing, accepting, and denying applications for accessory dwelling units (ADUs). ADUs and junior accessory dwelling units (JADUs) that are created pursuant to Section 66323 are commonly referred to as “State Exempt” or “State Mandated” ADUs.

Generally, a local agency may impose certain standards by local ordinance for the approval of ADUs, pursuant to Government Code section 66314. However, pursuant to Section 66323, there are four types of State Exempt ADUs for which local agencies must ministerially approve an application for a building permit within residential and mixed-use zones:

(1) One JADU within an existing or proposed single-family home and an ADU within an existing or proposed single-family home or an existing accessory structure if the proposed unit has an independent exterior access from the existing residence and the side and rear setbacks are sufficient for fire and safety;

(2) One detached, new construction ADU that does not exceed four-foot side and rear yard setbacks for a lot with a proposed or existing single-family dwelling and which conforms to specified height and size requirements;

(3) ADUs within portions of existing multi-family dwellings that are not used as livable space; and

(4) Up to two detached ADUs on a lot that has a proposed multifamily dwelling, or up to eight detached ADUs on a lot with an existing multifamily dwelling, not to exceed the number of existing units on the lot, subject to specified height and setback requirements.

ADUs outside the four State Exempt categories must adhere to the standards established in a local agency’s ordinance, provided it complies with Government Code section 66314. However, if there is no valid ordinance in place, any proposed ADU development will be regulated solely by State ADU law.

In addition to the above, the California legislature has recently passed several critical measures which have an impact on ADU laws, including, but not limited to:

• AB 976: Prohibits a local agency from requiring owner-occupancy for an ADU.
• AB 1033: Authorizes a local agency to adopt a local ordinance to allow the separate conveyance of the primary dwelling unit and ADUs.
• AB 1332: Among other things, requires local agencies to approve or deny an application for a detached ADU that utilizes a preapproved plan, or an identical plan in a previously approved application for a detached ADU, within 30 days.
• AB 434: Authorizes the California Department of Housing and Community Development to enforce ADU laws.
• AB 345: Imposes certain conditions for the separate conveyance of ADUs from the primary dwelling.
• AB 3182: Among other things, deems applications for the creation of an ADU or JADU approved if the local agency has not approved or denied the completed application within sixty (60) days.

Takeaways

ADU laws have lately gone through a host of changes, some minor and some major, prompting local agencies to continually review their existing ordinances and permitting practices for any necessary changes in light of the legal updates. Local agencies should be cognizant of the specific requirements in Section 66323, as it carves out a critical exemption limiting local agencies’ authority over ADU design standards.

If you have any questions about the changes to Section 66323, other changes in ADU law, or local planning and zoning in general, please contact one of the authors of this Client News Brief or any attorney at one of our eight officeslocated statewide. You can also subscribe to our podcasts, follow us on Facebook, X (formerly Twitter), and LinkedIn, or download our mobile app.