New California ADU Laws for 2026: Every Change Homeowners Need To Know

California’s ADU regulations changed significantly on January 1, 2026. From tighter JADU rules to stronger enforcement penalties, here’s a complete breakdown of every new ADU law, what it means for homeowners, and how these updates affect your next project.

If you have been tracking ADU laws in California through 2025, you already know the pace of change has been extraordinary.

California has passed more ADU legislation in the last three years than in the previous two decades combined.

In 2025 alone, Governor Newsom signed four new accessory dwelling unit bills into law (AB 462, AB 1154, SB 9, and SB 543), each targeting a different friction point in the ADU permitting and construction process.

Three of those bills took effect on January 1, 2026. One (AB 462) took immediate effect as an urgency measure when it was signed on October 10, 2025.

Combined with the 2025 updates that preceded them (SB 477, AB 2533, SB 1211, and AB 1332), California’s ADU framework looks fundamentally different than it did just two years ago.

Whether you are planning a detached backyard unit, a garage conversion, or a junior ADU inside your existing home, understanding these changes is critical before you begin.

This guide covers every major update to ADU laws in California for 2025 and 2026, organized by bill, with a clear explanation of how each change affects homeowners in practice, including shifts in ADU zoning laws, permitting timelines, and building requirements.

What Changed on January 1, 2026: The Four New ADU Bills

AB 462: Coastal Development Permits and Disaster Rebuilds

AB 462 was the most immediately impactful of the 2025 bills because it was enacted as an urgency measure, taking effect the moment Governor Newsom signed it on October 10, 2025.

It addresses two areas that had been creating significant bottlenecks: Coastal Development Permits (CDPs) and certificate of occupancy rules in disaster areas.

Coastal Development Permit Overhaul

Before AB 462, building an ADU in the California Coastal Zone often meant navigating a lengthy and unpredictable CDP process, including the possibility of appeals to the California Coastal Commission. AB 462 changes that in several key ways:

• 60-day approval clock: Local agencies with a certified Local Coastal Program (LCP) must now approve or deny a completed CDP application for an ADU within 60 days, which is the same timeline that applies to ADU building permits statewide.
• No more Coastal Commission appeals: The ability to appeal an ADU’s CDP to the Coastal Commission has been eliminated, removing what was often a months-long delay.
• Streamlined Commission review: If a local agency doesn’t have a certified LCP, it must immediately notify the Coastal Commission when an ADU application is submitted. The Commission’s review is also subject to a 60-day shot clock, with limited exceptions.

Certificate of Occupancy for Disaster-Affected Properties

Under existing law, a detached ADU generally cannot receive a certificate of occupancy (CofO) before the primary dwelling on the same lot. AB 462 creates a narrow but important exception for disaster areas:

If the Governor has declared a state of emergency for the county on or after February 1, 2025, the primary dwelling was substantially damaged or destroyed by the event referenced in that proclamation, and the ADU has been issued construction permits and passed all required inspections, then the detached ADU can receive a CofO before the primary dwelling is rebuilt.

This provision is directly relevant to homeowners affected by events like the Los Angeles wildfires.

If you lost your home and are working with an ADU builder in Los Angeles, such as LADU, to add a backyard unit, you may be able to occupy the ADU while your main residence is being reconstructed.

AB 1154: Junior ADU Owner-Occupancy and Short-Term Rental Ban

AB 1154 makes two significant changes to how junior accessory dwelling units (JADUs) are regulated in California.

Owner-Occupancy Rule Revised

Previously, the owner of a property with a JADU was generally required to reside on the property. AB 1154 narrows this requirement substantially:

• If the JADU shares sanitation facilities (a bathroom) with the primary single-family dwelling, the property owner must still reside on the property.
• If the JADU has its own bathroom, there is no owner-occupancy requirement.

This is a meaningful distinction for homeowners who build a self-contained junior ADU with its own bath, as they are now free to rent both the main home and the JADU without living on-site.

Short-Term Rental Prohibition for JADUs

AB 1154 prohibits JADUs from being used as short-term rentals (rentals of fewer than 30 consecutive days). This restriction applies to all JADUs statewide, regardless of local short-term rental ordinances.

The bill extends this prohibition beyond JADUs as well. Every ADU approved under Government Code section 66323 (the conversion/exemption category) must also be rented for terms longer than 30 days.

Local agencies can choose to apply this same restriction to ADUs created under the standard provisions of Government Code sections 66314 through 66322.

SB 9 (2025): Enforcement Penalties for Non-Compliant Local Agencies

This bill shares its name with the well-known 2021 SB 9 (the lot-split/duplex law) but is separate legislation addressing a different issue: state enforcement of ADU compliance.

What SB 9 (2025) Does

When California passed its ADU laws, it required cities and counties to submit their local ADU ordinances to the California Department of Housing and Community Development (HCD) for review.

Many jurisdictions either failed to submit their ordinances on time or did not fix violations identified by HCD.

SB 9 (2025) adds teeth to that requirement:

• If a local agency fails to submit its ADU or JADU ordinance to HCD within the required timeframe, the local ordinance is rendered null and void.
• If HCD identifies violations and the local agency fails to correct them, the ordinance is also rendered null and void.
• When a local ordinance is voided, only state ADU law applies, meaning the jurisdiction must follow the state’s baseline regulations without any local modifications.

Why This Matters

This effectively eliminates the ability of non-compliant cities to enforce restrictive local ADU rules. If your city has been slow-walking ADU approvals based on questionable local interpretations, SB 9 (2025) may have already invalidated those rules.

SB 543: Permit Timelines, Impact Fees, and Size Measurement

SB 543 is the most technically detailed of the four bills, touching on multiple aspects of ADU regulation.

Tighter Permit Processing Timelines

SB 543 strengthens California’s existing ADU “shot clock,” i.e., the requirement that local agencies process ADU permits ministerially within 60 days:

• 15-business-day completeness review: Within 15 business days of receiving an ADU application, the city or county must determine whether the application is complete and issue written notice.
• Itemized deficiency list: If the application is incomplete, the agency must list exactly what’s missing and explain how to correct it.
• No new requirements on resubmission: Once the applicant resubmits a corrected application, the agency cannot introduce new requirements beyond what was originally listed.
• 60-business-day dispute resolution: If the applicant disputes a completeness determination or denial, the agency must issue a final written decision within 60 business days.
• Deemed-complete default: If the agency fails to respond within the required timeframe, the application is deemed complete by default.

This is designed to end the practice of “incompleteness cycling,” where cities would repeatedly reject ADU applications with new deficiency items to delay approval indefinitely.

Impact Fee Clarifications

SB 543 further refines California’s rules on ADU impact fees:

• No impact fees can be charged on ADUs of 750 square feet or smaller.
• No impact or school fees can be charged for JADUs.
• For ADUs over 750 square feet, fees must be charged proportionally based on the size of the ADU compared to the primary dwelling. Flat or arbitrary fee schedules are no longer permitted.
• Any ADU or JADU under 500 square feet does not increase assessable space, which affects property tax and school fee calculations.

Interior Livable Space Measurement

SB 543 clarifies that ADU size limits are measured by interior livable space, not exterior walls, garage areas, structural wall thickness, or attic areas with low ceiling heights. This prevents cities from inflating square footage calculations to push an ADU over the size threshold.

Fire Sprinkler Alignment for JADUs

SB 543 amends fire sprinkler requirements so that JADUs follow the same rules as standard ADUs. A JADU cannot trigger a sprinkler requirement if the primary home doesn’t already have sprinklers installed.

2025 ADU Law Changes Still in Effect

The 2026 updates build on several important changes that took effect on January 1, 2025. Understanding these provides essential context for the current regulatory framework.

SB 477: Government Code Renumbering

All California ADU and JADU laws were moved from Government Code section 65852 to sections 66310 through 66342. This is a housekeeping change, but it means older references to section 65852 are now outdated.

AB 2533: Unpermitted ADU Legalization

Local agencies can no longer deny permits for unpermitted ADUs that were built before January 1, 2020, solely because the ADU was unpermitted, unless there is a genuine safety concern.

Agencies must publish checklists and guidance on how homeowners can bring older ADUs into compliance.

SB 1211: Multifamily ADU Expansion

The maximum number of detached ADUs allowed on multifamily properties was increased to eight, provided the number of new ADUs doesn’t exceed the number of existing dwelling units on the property.

AB 1332: Pre-Approved ADU Plans and Setbacks

AB 1332 introduced several changes that are now part of the baseline ADU framework:

• Pre-approved plan mandate: Every local agency must develop a program for the pre-approval of ADU plans. Agencies must accept plan submissions from any party, post approved plans on their website, and process applications using pre-approved plans within 30 days (versus 60 days for standard plans).
• Cross-jurisdictional plans: Agencies may also accept ADU plans that have been pre-approved by other local or state agencies.
• Relaxed setbacks and height: Cities must allow at least an 800-square-foot ADU with 4-foot side and rear setbacks, even if the ADU doesn’t meet other lot coverage, FAR, or front setback requirements.
• Parking elimination: If uncovered off-street parking is removed to build an ADU, replacement parking isn’t required.

AB 976: Permanent Owner-Occupancy Prohibition

The previous prohibition on owner-occupancy requirements for standard ADUs had a sunset date of January 1, 2025. AB 976 removed that sunset entirely, making the prohibition permanent.

Local agencies can never require that the property owner live in either the primary dwelling or the ADU as a condition of ADU approval.

Standing California ADU Regulations: The Complete Baseline

Beyond the recent legislative updates, the standing ADU regulations in California include zoning laws, building codes, setback rules, and permitting requirements that form the foundation of every ADU project.

Here’s the complete baseline every homeowner should understand.

ADU Types Allowed

California recognizes three categories of accessory dwelling units:

• Detached ADU: A standalone structure separate from the primary dwelling, such as a backyard cottage or converted garage.
• Attached ADU: A unit built onto or within an existing primary dwelling, such as a room addition with a separate entrance.
• Junior ADU (JADU): A small unit of no more than 500 square feet of interior livable space, built within the walls of an existing single-family home or attached accessory structure. Must include an efficiency kitchen (sink, cooking appliance, counter, and storage) but may share a bathroom with the main dwelling.

Number of ADUs Allowed

For single-family lots:

• One standard ADU (detached or attached)
• One conversion ADU (converted from existing space such as a garage)
• One JADU
• An 800-square-foot detached ADU is allowed by right, even if lot coverage or FAR limits would otherwise prevent it

For multifamily lots:

• Up to eight detached ADUs (not exceeding the number of existing units on the property)
• Interior conversion ADUs within existing non-livable space (laundry rooms, storage, etc.)

Size Limits

Note: Per SB 543, all size measurements are based on interior livable space, not exterior dimensions.

Height Limits

• Detached ADU (single-family or multifamily lot): Up to 16 feet
• Detached ADU within ½ mile of a major transit stop or high-quality transit corridor: Up to 18 feet, plus an additional 2 feet if the roof pitch matches the primary dwelling
• Detached ADU on a lot with a multifamily, multi-story dwelling: Up to 18 feet
• Attached ADU: Up to 25 feet or the height limitation of the primary dwelling, whichever is lower

Setback Requirements

• Side and rear setbacks: 4 feet for ADUs of 800 square feet or less
• Front setback: State law doesn’t specify a minimum front setback for ADUs, but local agencies may have requirements. However, cities must allow at least an 800-square-foot ADU, even if it encroaches on the front setback, provided there’s no other feasible location.
• Distance from existing structures: This varies by local building code and fire safety requirements.

Parking Requirements

California ADU law significantly limits what local agencies can require for ADU parking:

• No parking required if the ADU is within a half-mile of public transit, in a historic district, part of an existing primary residence, in an area where on-street permits are required but not offered to ADU occupants, or within one block of a car-share vehicle.
• A maximum of one space can be required in other situations.
• If existing uncovered parking is displaced by ADU construction, replacement parking is not required.

ADU Permit Timeline

Impact Fees

• ADUs ≤ 750 sq. ft.: Exempt from impact fees
• JADUs: Exempt from impact and school fees
• ADUs > 750 sq. ft.: Impact fees must be proportional to the ADU’s size relative to the primary dwelling
• ADUs and JADUs < 500 sq. ft.: Do not increase assessable space for property tax or school fee purposes

Owner-Occupancy Rules

• Standard ADUs: No owner-occupancy requirement can ever be imposed (AB 976, permanent prohibition).
• JADUs with shared bathroom: Owner must reside on the property.
• JADUs with separate bathroom: No owner-occupancy requirement (AB 1154).

Short-Term Rental Restrictions

• JADUs: Cannot be used as short-term rentals (less than 30 days). Statewide prohibition under AB 1154.
• Conversion/exemption ADUs (Gov. Code § 66323): Cannot be used as short-term rentals.
• Standard ADUs: Local agencies may choose to extend the 30-day minimum rental restriction. Check your local ordinance.

HOA and CC&R Restrictions (AB 130)

Homeowners associations and CC&Rs may impose “reasonable restrictions” on ADU construction, but they cannot include fees or financial requirements related to the ADU.

If your HOA is charging extra fees or assessments specifically because of your ADU, that likely violates state law.

Fire Sprinkler Requirements

• ADUs are not required to have fire sprinklers unless the primary dwelling is also required to have them.
• JADUs follow the same rule (updated by SB 543).

Coastal Zone ADUs

ADUs in the California Coastal Zone are subject to state ADU law. Under AB 462, CDPs for ADUs must be processed within 60 days, and appeals to the Coastal Commission have been eliminated for agencies with certified LCPs.

The California Coastal Commission is required to provide guidance to local agencies on updating their programs to streamline ADU approvals by July 1, 2026 (SB 1077).

What’s Coming Next: ADU Legislation on the Horizon

California’s ADU regulatory environment continues to evolve. Several provisions are scheduled to take effect in the coming years, and additional legislation is under discussion.

Confirmed Future Changes

• Online Permit Portals (AB 920): Jurisdictions with a population of 150,000 or more must create centralized online permit application portals that allow homeowners to submit and track ADU applications. Most jurisdictions must launch these systems by January 1, 2028, with a possible extension to January 1, 2030 for agencies that formally document cost concerns and begin procurement.
• Coastal Guidance (SB 1077): The California Coastal Commission must provide local municipalities with clear guidance on revising their local coastal programs to streamline ADU approvals. The deadline is July 1, 2026.
• Third-Party Plan Review (AB 253): If a jurisdiction takes more than 30 business days to review a complete ADU building permit application, the applicant may hire a certified private plan checker and force a decision within 10 business days. This provision extends through 2036.
• Historic District Protection (AB 1061): Cities can only deny ministerial ADU processing if the actual property is individually listed as a historic resource or landmark. Being located inside a historic district overlay alone is no longer sufficient to force discretionary review.
• AB 1033 for ADU Condo Conversions: Enacted in 2023, AB 1033 removed the state-level ban on selling ADUs as separate condominiums. However, the law requires each city and county to opt in individually. As of mid-2026, San Diego is among the first major cities to adopt an AB 1033 ordinance (effective August 2025). Other cities are expected to follow, but the process involves condominium subdivision, HOA formation, and potentially California Department of Real Estate (DRE) review, with soft costs ranging from $50,000 to $75,000.

Proposed Bills Under Discussion

Several additional bills are being discussed in the California Legislature that could further shape ADU policy:

• AB 1208: Proposed changes to ADU permitting and fee structures
• AB 1294: Additional ADU regulatory amendments
• SB 315: Potential further ADU policy updates
• Additional fee reductions for small ADUs
• Simplified utility connection processes
• Enhanced tenant protections for ADU occupants

Key Entities and Agencies To Know

Understanding who oversees ADU regulation in California helps when navigating the process:

• HCD (California Department of Housing and Community Development): The state agency responsible for enforcing ADU law compliance. HCD reviews local ADU ordinances, publishes the official ADU Handbook (most recently updated March 2026), and can void non-compliant local ordinances.
• California Coastal Commission: Oversees Coastal Development Permits in the Coastal Zone. AB 462 significantly reduced the Commission’s role in ADU permitting.
• Local Planning and Building Departments: Handle day-to-day ADU permit review. Must follow state timelines and cannot impose restrictions more stringent than state law.
• California Government Code, Chapter 13 (§§ 66310–66342): The statutory home of all state ADU and JADU laws, renumbered by SB 477 in 2025.

How These Changes Affect Los Angeles Homeowners

Los Angeles homeowners stand to benefit significantly from the 2025 and 2026 ADU law updates.

The city’s housing shortage, combined with high construction costs and complex permitting, has historically made ADU projects challenging. The new laws address several of these pain points:

• Faster permitting through the 15-day completeness requirement and 60-day shot clock ensures projects aren’t stalled by bureaucratic delays.
• Pre-approved plans offer a faster track to approval, with many plans now publicly accessible through the city’s ADU portal.
• Disaster rebuild provisions (AB 462) allow homeowners affected by events like the 2025 LA wildfires to occupy a detached ADU while rebuilding their primary home.
• Reduced fees for ADUs under 750 square feet and proportional fee structures for larger units make projects more financially viable.
• Permanent owner-occupancy prohibition means investment-minded homeowners can rent both the main house and the ADU without residing on the property.

The combination of statewide streamlining and LA’s own evolving ADU resources creates a favorable environment for homeowners considering their first, or next, ADU project.

Bottom Line

California’s ADU laws are now the most homeowner-friendly in the country.

The 2026 updates closed many of the remaining loopholes that cities used to delay or block compliant projects, established clearer measurement standards, tightened permitting timelines, and extended new protections to coastal and disaster-affected properties.

If you’re considering adding an ADU to your property, the regulatory environment has never been more favorable. The key is understanding how these state laws interact with your local city or county’s specific ordinances and working with professionals who stay current on both.