California ADU laws are changing again, and 2026 brings several important updates homeowners should know about. While recent years focused on making ADUs legal almost everywhere, the newest laws fine-tune how cities process permits, apply fees, regulate rentals, and handle ADUs in special areas like the coast or disaster-affected zones.

Three new bills, SB 543, AB 1154, and AB 462, build on existing ADU rules and close loopholes that were causing confusion, delays, or inconsistent enforcement across cities. Some of these changes can lower costs, speed up approvals, and make ADUs and JADUs more flexible long-term housing options.

We’re breaking down what each new law does, when it takes effect, and what it means if you’re planning to build an ADU in California in 2026 or beyond.

A Quick Overview of ADU Laws in 2026

The 2026 ADU updates are not a full overhaul. Instead, they:

  • Clarify rules that cities were interpreting inconsistently
  • Reinforce state authority over local ADU ordinances
  • Close loopholes related to fees, rental use, and permit delays

Most of the changes take effect January 1, 2026, with some provisions already active. Importantly, these laws apply statewide and override local rules that conflict with them.

SB 543: Clarifying ADU Standards and Reducing Small-Unit Costs

SB 543 is largely a cleanup and clarification bill, but those clarifications matter.

What SB 543 Does For ADUs

1. Clarifies how ADU size is measured

SB 543 makes clear that maximum ADU and JADU size allows interior livable space only, excluding wall thicknesses. This resolves a common issue where cities were calculating size differently, sometimes shrinking what homeowners could build.

2. Limits school impact fees for small ADUs under 500 sq ft

ADUs under 500 square feet are exempt from school impact fees. For smaller or budget-focused ADUs, this can result in meaningful savings.

3. Reinforces ministerial approval timelines

Cities must process ADU permits ministerially and within state-mandated timelines. SB 543 strengthens compliance by requiring local ordinances to align with state law.

4. Cities must review ADU and JADU applications within 15 business days

Under this update, permitting agencies are required to review ADU and JADU applications for completeness within 15 business days of submission. If anything is missing, the city must provide written notice identifying exactly what’s incomplete and how to fix it. Homeowners are then allowed to correct and resubmit without restarting the process.

This applies even in cities that haven’t adopted a local JADU ordinance, ensuring JADU applications are still processed ministerially under state law.

Why SB 543 Matters

SB 543 reduces ambiguity which is one of the biggest causes of ADU delays. It also protects homeowners from unnecessary fees and local interpretations that conflict with state law.

AB 1154: Changes to JADUs, Rentals, and Owner-Occupancy

AB 1154 is narrowly focused on Junior ADUs (JADUs). It does not change how standard ADUs are treated when it comes to short-term rentals, but it does make a meaningful update to owner-occupancy rules for JADUs.

What AB 1154 Changes

1. Owner-occupancy is no longer required for certain JADUs

Under AB 1154, owner-occupancy cannot be required for a JADU if the unit has its own bathroom and does not share sanitation facilities with the primary home. This is a significant shift from prior rules, which often required the homeowner to live on-site when a JADU was present.

For homeowners, this makes JADUs more viable as true long-term housing units rather than informal or limited-use spaces.

2. JADUs are still prohibited from short-term rentals

AB 1154 does not change the long-standing rule that JADUs cannot be rented for fewer than 30 days. Cities are still prohibited from allowing JADUs to be used as vacation rentals.

However, it’s important to clarify what this bill does not do:

  • Cities may still choose whether to allow ADUs (not JADUs) to be used as short-term rentals.
  • AB 1154 applies only to JADUs, not standard ADUs.

Why AB 1154 Matters

The owner-occupancy change is a big deal for homeowners who want more flexibility. By removing mandatory owner-occupancy in certain JADU setups, the law makes JADUs easier to finance, rent, and plan for long-term use while still maintaining restrictions that prevent them from becoming short-term vacation rentals.

AB 462: Emergency ADU Relief for Los Angeles Coastal Areas

AB 462 is a targeted, emergency response law passed in the wake of the Palisades fire and similar disasters. Unlike other ADU legislation, this bill is specifically focused on Los Angeles County and certain disaster-affected areas and it temporarily overrides parts of the California Coastal Act to speed up housing recovery.

What AB 462 Does

1. Exempts ADUs in Los Angeles County from Coastal Development Permits

Under AB 462, the construction of an ADU in Los Angeles County is exempt from the requirement to obtain a Coastal Development Permit (CDP) if the property is located in the coastal zone.

This is a major departure from existing law, which normally requires coastal ADUs to comply fully with the California Coastal Act and obtain a CDP, often one of the biggest sources of delay.

2. Applies to disaster-declared counties after February 1, 2025

In addition to Los Angeles County, the exemption may also apply to any county subject to a Governor-declared state of emergency on or after February 1, 2025, as specified in the bill.

3. Applies to all cities, including charter cities

AB 462 explicitly states that this law addresses a matter of statewide concern, meaning it applies to all cities within Los Angeles County, including charter cities that would otherwise claim local control.

4. Takes effect immediately

This bill is an urgency statute, meaning it went into effect immediately upon being signed. Not in 2026. The goal is to accelerate housing recovery without waiting for a future implementation date.

Why AB 462 Matters

In coastal areas of Los Angeles, ADU projects have historically faced longer timelines, higher costs, and greater uncertainty due to Coastal Act requirements. After the Palisades fire, those barriers became even more problematic for homeowners trying to rebuild or add housing quickly.

AB 462 removes one of the biggest obstacles, the Coastal Development Permit, making it faster and more feasible to build ADUs in affected coastal communities during recovery.

For homeowners in Los Angeles considering an ADU after a disaster, this bill can significantly reduce red tape and shorten the path from planning to construction.

ADU Laws in 2026 Continue the Same Trend

The 2026 California ADU laws don’t reverse course. They continue the state’s long-term push to make ADUs easier, faster, and more predictable to build. By tightening definitions, limiting fees, and enforcing timelines, these laws remove friction that has slowed projects in the past.

For homeowners, that means less uncertainty and more confidence moving forward, especially when working with experienced ADU professionals who understand how to apply state law locally.

If you want to stay ahead of future ADU law changes, Maxable hosts monthly webinars covering the latest updates to California ADU regulations, local permitting trends, and what homeowners should know before building. These sessions are designed to break down complex rules into clear, practical guidance, so you can make informed decisions with confidence.

Sign up for Maxable’s upcoming ADU webinars to stay up to date on new laws, policy changes, and real-world impacts for homeowners.