Can I appeal if the city denies my ADU permit or says my application is incomplete?

Yes. Since January 1, 2026, state law requires every agency that reviews ADU permits to offer a written appeal process for both incomplete determinations and denials. The agency must issue a final written decision on your appeal within 60 business days of receiving it.

Where the appeal right comes from

SB 543 (2025) amended Government Code section 66317, the core ADU permit-processing statute. Under subdivision (d), if your application is found incomplete or is denied, the permitting agency must let you appeal in writing to its governing body, or to its director if it has no governing body. Cities and counties must direct appeals to the city council or board of supervisors or, at their option, the planning commission, or both. Offering two levels of appeal does not extend the 60-business-day deadline. Section 66335 gives junior ADU (JADU) applicants the same right.

What the agency must give you first

• A completeness decision within 15 business days. The agency must tell you in writing whether your application is complete. If it is not, the notice must list the missing items and explain how to fix them.
• No moving target. When you resubmit, the agency cannot ask for an item that was not on that list, and it has another 15 business days to check the resubmittal. If it misses either deadline, the application is deemed complete.
• A full set of comments on denial. If the agency denies a complete application, it must, within the 60-day review period, give you in writing every item it considers defective or deficient and describe how you can remedy each one.

When an appeal makes sense

Most corrections are ordinary plan-check comments, and answering them with revised sheets is usually faster than appealing. An appeal is worth considering when you believe the agency:

• asked for something state ADU law does not allow, such as a standard that is not objective;
• added a new requirement on resubmittal that was not on the original incomplete list; or
• relied on a local rule other than an ADU ordinance that complies with state law, which section 66317(c) prohibits as a basis for delay or denial.

Ask the agency for its written appeal procedure, filing deadline and any fee before you file. HCD also accepts technical-assistance requests about denials through its ADU Portal, but its handbook says you should first work through the local agency's process, and HCD may not follow up with an agency when no application is pending.

What this means for your MEP plans and permit set

Common reasons for an incomplete notice are missing or inconsistent technical documents: no electrical load calculation, a Title 24 report that does not match the equipment shown, or plumbing sheets without the drain, waste and vent layout. Closing those gaps before you submit keeps an appeal as a last resort rather than a routine step, and if you do appeal, a coordinated MEP set lets you show that every listed item was addressed. See how the 60-day rule works, what belongs in a complete ADU application, and the California ADU permit guide. Appeal procedures vary, so confirm the details with your planning or building department.

Sources: leginfo.legislature.ca.gov, leginfo.legislature.ca.gov, hcd.ca.gov.