The short answer: A California city cannot simply say no to an ADU. It must review the application ministerially, decide within 60 days of a complete application and, if it denies it, return in writing a full set of comments listing what is deficient and how to fix it. Since January 1, 2026, cities must also offer a written appeal, with a final decision within 60 business days. If the city misses the 60-day deadline, the application is deemed approved. If the problem is the city’s ordinance itself, the state housing department can review it.
Last verified: October 29, 2026 · Written by Marc
This guide summarizes California Government Code sections read on October 29, 2026. It is general information, not legal advice. Your city’s procedures and deadlines for appeals are set locally within the state framework, so read the denial carefully and consider a land use lawyer if the stakes are high.
A denial letter is discouraging, but for an ADU it is rarely the end. State law treats ADUs differently from most building projects: the review is ministerial, the deadlines are short and the city has to explain itself. Most denials come down to fixable items, such as missing documents, a design that misses an objective standard, or a misunderstanding about which rule applies. This guide explains what the city owes you, how to respond, how the new appeal process works and when to involve the state.
What the city owes you by law
Government Code § 66317, as amended by SB 543 for 2026, sets the process:
| Stage | What the law requires |
|---|---|
| Review type | Ministerial, without discretionary review or a hearing |
| Completeness check | Written notice within 15 business days of whether the application is complete |
| If incomplete | A list of incomplete items and how to make the application complete |
| On resubmission | The city cannot ask for items that were not on its list |
| Late completeness decision | The application is deemed complete |
| Decision | Approve or deny within 60 days of a complete application, if there is an existing home on the lot |
| Late decision | The application is deemed approved |
| Denial | A full set of written comments listing defective or deficient items and how to remedy them, within the same 60 days |
| Basis for denial | Only an ADU ordinance consistent with state law, not other local rules |
| Appeal | A written appeal process, with a final written determination within 60 business days |
If the ADU is submitted together with a new home on the lot, the city may wait to decide the ADU until it decides the new home. If you ask for a delay, the 60-day clock stops for that period.
Step 1: read the denial against the law
Start by checking what the city actually sent:
- Is it a denial or an incomplete notice? An incomplete notice is about missing items; a denial is a decision on a complete application. The remedies differ.
- Did it arrive on time? Count from the date the application was complete. A decision after 60 days, without a delay you requested, triggers the deemed-approved rule.
- Does it list each deficiency and how to fix it? The law requires both. A one-line rejection does not meet that standard.
- Which rule does each comment cite? The law limits the basis for denial to an ADU ordinance consistent with the state’s ADU law.
Write down each comment, the rule it cites and whether you agree. That list becomes your response or your appeal.
Common mistake: treating a list of plan check comments as a final denial and starting over. Many “denials” are really a list of corrections. Responding point by point to the city’s own list is usually the fastest route to approval, and the city cannot add new items to an incomplete list when you resubmit.
Step 2: fix what can be fixed
Most comments fall into one of three groups:
- Missing or unclear documents. A site plan without setbacks, an energy report, a utility letter. Supply them and note where each one is in the resubmittal.
- Design issues under objective standards. Height, setbacks or size that miss a standard. Check whether the standard is one the state allows. Our guides to ADU setbacks and height limits set out the state limits.
- Rules the city may not apply. For example, a parking requirement for an ADU near transit, or an owner occupancy condition on an ordinary ADU. Point to the state rule in your response; see our guides to ADU parking requirements and owner occupancy rules.
Respond in writing, item by item, and ask the city to confirm the date your resubmittal was received.
Step 3: appeal in writing if you disagree
Since January 1, 2026, § 66317(d) requires every permitting agency to provide a written appeal process when it finds an ADU application incomplete or denies it. For a city or county, the appeal goes to the governing body or, at the local agency’s option, the planning commission, or both. The agency must issue a final written determination no later than 60 business days after it receives your written appeal. Allowing appeals to both bodies does not extend that period.
An effective appeal usually includes:
- The application number and dates: submitted, deemed complete and denied.
- Each denial comment, the rule it relies on and why you disagree.
- The state rule that supports your position, with the code section.
- What you have already changed in response.
- A clear request: approval, or approval with stated conditions.
Practical tip: Ask your city for its written ADU appeal procedure the day you receive a denial. The state sets the 60-business-day limit for the decision, but the city sets details such as forms, fees and filing deadlines, and missing a local deadline can cost you the appeal.
Step 4: when the state can step in
California’s Department of Housing and Community Development (HCD) has two roles relevant to ADU denials:
- Ordinance review, § 66326. Cities must send their ADU ordinances to HCD within 60 days of adoption. HCD can issue written findings that an ordinance does not comply with state law, and the city must amend it or explain why it disagrees. If the city does neither, HCD may notify the Attorney General. An ordinance the city fails to submit, or whose findings it fails to answer within 30 days, is null and void, and the city must apply the state’s ADU standards instead.
- Enforcement, § 65585(j). HCD may notify the Attorney General when a local government takes an action that violates the state’s ADU law, which is listed among the housing laws HCD enforces.
HCD publishes its review letters to cities on its website. If your denial rests on a local rule that seems to conflict with state law, those letters show how HCD has treated similar rules elsewhere.
A worked example
Here is a hypothetical case. An owner applies for a 750 sq ft detached ADU. The city deems the application complete on March 2. On April 20, within the 60 days, it denies the application with two comments: the plans lack a drainage plan, and the ADU must provide one parking space.
- Comment 1 is a fixable document issue. The owner adds a drainage plan.
- Comment 2 may conflict with state law if the lot is within one-half mile walking distance of public transit, where cities cannot require ADU parking. The owner cites the state rule and the transit stop’s distance.
The owner resubmits with a point-by-point response. If the city maintains the parking requirement, the owner files a written appeal, and the city must issue its final determination within 60 business days.
Frequently asked questions
Can a California city deny an ADU permit?
Yes, but only on grounds consistent with the state’s ADU law, and with an explanation. The city must review the application ministerially, decide within 60 days of a complete application and, if it denies it, return a full set of written comments listing what is deficient and how to remedy it. It cannot rely on local rules outside a compliant ADU ordinance.
What happens if the city doesn’t decide in 60 days?
If there is an existing home on the lot and the city has not approved or denied a complete application within 60 days, the application is deemed approved under Government Code section 66317. The clock pauses if you request a delay, and it works differently when the ADU is submitted with a new home on the lot.
How do I appeal an ADU denial?
Since January 1, 2026, every permitting agency must offer a written appeal of an ADU denial or incomplete finding. For cities and counties, the appeal goes to the governing body or the planning commission, or both. The agency must issue a final written decision within 60 business days. Ask the city for its procedure, forms and filing deadline immediately.
Can I file a complaint with the state?
The state housing department, HCD, reviews local ADU ordinances and may notify the Attorney General when a local government violates the state’s ADU law. HCD publishes its review letters to cities. If a denial rests on a local rule that conflicts with state law, contact HCD and describe the rule, the city and your application.
Should I hire a lawyer after an ADU denial?
Not always. Many denials are fixable with a point-by-point response. A land use lawyer is worth considering when the city relies on a rule that seems to conflict with state law, when deadlines have passed without a decision, or when an appeal fails. Bring the application, the denial and your response to the first meeting.
The bottom line
An ADU permit denied in California is usually the start of a conversation, not the end of the project. The city must decide within 60 days of a complete application, explain any denial in writing with a way to fix it, and since 2026 offer a written appeal decided within 60 business days. A late decision means the application is deemed approved. HCD can review ordinances that conflict with state law.
Your next step is to compare each denial comment with the state rule it relies on and respond in writing. Use our ADU permit application checklist for the resubmittal and our guide to how long an ADU permit takes to track the dates.
Sources
- Cal. Gov. Code § 66317 (as amended by SB 543, effective 2026)
- Cal. Gov. Code § 66326 (HCD ordinance review)
- Cal. Gov. Code § 65585 (HCD enforcement)
- Cal. Gov. Code § 66322 (parking)
General information, not legal advice. Local rules vary and change; confirm with your planning department.
Cover photo: “SD17Gallery of Houses (36773185824)” by U.S. Department of Energy Solar Decathlon, public domain, via Wikimedia Commons.
Questions or a correction?
If something in this guide is unclear, out of date or does not match what your city told you, send me a message. Include the source if you have one.