New ADU Permit Rules in 2026: How SB 543's 15-Day Completeness Deadline Speeds Up Your San Diego Project
Ask any homeowner in San Diego who’s gone through the ADU permitting process and you’ll hear the same story: long waits, unclear feedback, and no real way to hold the city accountable. Senate Bill 543, signed by Governor Newsom and effective January 1, 2026, changes the game. It sets a hard deadline for cities to review your ADU or JADU application – and for the first time, gives you a formal right to appeal if things go sideways.
Why This Law Was Needed
Under previous California law, local agencies had 60 days to approve or deny a complete ADU application. The catch? There was no deadline for how long a city could take to decide whether your application was complete in the first place. Some jurisdictions would take weeks or even months before issuing an incompleteness determination, and every time they flagged something new, the 60-day approval clock would reset.
There was also no formal process for challenging a denial or disagreeing with an incompleteness finding. For homeowners and builders in San Diego, this created a frustrating cycle of delays with no accountability. According to the Department of Housing and Community Development (HCD), over 50 local governments across California have incorrectly applied state ADU and JADU laws resulting in inconsistent timelines and unnecessary permitting hurdles.
The Three Key Rules SB 543 Adds to ADU Permitting
1. Your Application Must Be Reviewed Within 15 Business Days
Once you submit your ADU or JADU permit application, the local permitting agency now has 15 business days – roughly three calendar weeks – to determine whether it is complete. They must provide you with written notice of that determination. If the agency doesn’t respond within the 15-day window, the application is deemed complete by operation of law.
2. Incomplete Applications Must Come With a Clear Fix List
If the agency finds your application incomplete, the written notice must include a detailed list of what’s missing and a description of how to make the application complete. You then get the chance to correct and resubmit. Each resubmittal triggers another 15-business-day review cycle so the city can’t sit on your corrections indefinitely.
3. You Now Have a Right to Appeal
This is the biggest change for applicants. If your ADU permit is denied or you disagree with an incompleteness determination, you can now file a written appeal. The permitting agency must issue a final written determination within 60 business days of receiving your appeal. No more accepting a denial with no recourse.
The New ADU Permit Timeline at a Glance
Here’s what the permitting process looks like from start to finish under SB 543:
Step | Deadline | What Happens |
|---|---|---|
Application submitted | Day 0 | Clock starts |
Completeness determination | 15 business days | City issues written notice – complete or incomplete with detailed list |
Resubmittal review (if needed) | 15 business days per resubmittal | City reviews corrected application on the same timeline |
Permit decision | 60 days after deemed complete | City must approve or deny |
Appeal (if denied or found incomplete) | 60 business days after appeal filed | City must issue final written determination |
With a clean, well-prepared application, you could go from submission to completeness confirmation in about three weeks, and from there to a permit decision within 60 days. That’s a real improvement over the open-ended waiting that many San Diego homeowners have experienced.
What This Means for San Diego ADU Projects
San Diego has been one of the most active ADU markets in California, with thousands of units permitted in recent years. But the permitting experience has not always matched that demand. Delays at the intake stage before the application is even formally under review have been a common source of frustration for homeowners and builders.
SB 543’s new rules change the dynamic in several important ways:
- Faster feedback: You’ll know within three weeks whether your application is on track or what needs to be corrected. No more months of silence.
- Clearer communication: If something is missing, the city must spell out exactly what and how to fix it. Vague or shifting feedback becomes much harder to justify.
- A real path to challenge decisions: The formal appeal process creates documented accountability. If your application is denied or unfairly flagged as incomplete, you have a structured way to push back.
- More predictable project planning: Defined deadlines at every stage mean you can schedule your contractor, lock in financing, and plan your construction timeline with much more confidence.
Tips for Getting Your San Diego ADU Application Approved Faster
The new timelines are on your side, but the fastest path to a permit is still a strong initial submission. Here’s how to set yourself up for success:
- Have your plans professionally reviewed before submitting: An experienced ADU consultant or architect can catch setback errors, missing calculations, and incomplete site plans before the city does – helping you avoid the resubmittal loop entirely.
- Understand San Diego’s local requirements: While SB 543 sets a statewide framework, the City of San Diego may still have local design standards and zoning overlay rules that apply. Make sure your plans address both.
- Document everything: The new appeal process depends on written records. Keep copies of every submission, correction notice, and communication with the planning department.
- Ask about the 15-day rule: Now that it’s law, don’t hesitate to ask your local planning office how they’re implementing it. Simply knowing the rule and showing that you know it can encourage compliance.
The Bottom Line
SB 543 gives ADU applicants in San Diego something they haven’t had before: enforceable timelines, clear written requirements, and a formal right to appeal. Whether you’re building a detached ADU, converting a garage, or adding a JADU, the permitting process just became a lot more predictable.
Ready to get your ADU project moving?
At SD CCS, we help homeowners across San Diego navigate every phase of the ADU process from design and permitting to construction and compliance.
Call us at (858) 727-5434 or schedule a consultation and let us help you take advantage of the new rules.
Disclaimer: This blog post is provided for informational purposes only and does not constitute legal advice. For guidance specific to your project, consult with a licensed professional or your local planning department.
