California's AB 2533: A New Pathway to Legalize Unpermitted ADUs

AB 2533: Legalizing California’s Unpermitted ADUs and Tackling the Housing Crisis 

California’s ongoing housing crisis has made Accessory Dwelling Units (ADUs) a cornerstone of the state’s strategy to expand housing options. These small, self-contained residential units—often built in backyards or converted garages—offer a relatively low-cost and efficient solution to the state’s shortage of affordable housing. But thousands of these units across the state were built without permits, either due to bureaucratic red tape, high permitting costs, or outdated local policies. Assembly Bill 2533 (AB 2533), signed into law in September 2024, directly addresses this challenge by offering a new pathway to legalize unpermitted ADUs and Junior ADUs (JADUs). 

This legislation represents a pragmatic shift in housing policy: instead of punishing homeowners for past noncompliance, it provides a clear, structured process for bringing unpermitted dwellings into the legal housing stock. This move not only increases housing availability but also enhances safety and equity for tenants and property owners alike. 

What Is AB 2533? 

AB 2533 expands on earlier efforts by California to legalize existing, unpermitted residential units. The state has long recognized that many ADUs provide critical housing, even if they weren’t originally built according to local codes. However, until now, only ADUs built before 

January 1, 2018 were eligible for certain amnesty protections. AB 2533 extends this eligibility cutoff date to January 1, 2020, significantly increasing the number of units that can benefit from this streamlined legalization process. 

Importantly, AB 2533 amends Government Code Section 66332 to ensure that local jurisdictions cannot deny permits for these units solely because they do not comply with certain building codes—unless those violations pose an actual health or safety risk as defined in Health and Safety Code Section 17920.3. 

This subtle but important distinction shifts the focus away from rigid code enforcement toward pragmatic safety improvements and housing preservation. 

Key Provisions of AB 2533 

1. Expanded Amnesty Eligibility 

Under AB 2533, any ADU or JADU built before January 1, 2020 without a permit is now eligible for legalization under this new framework. This opens the door for a significantly larger number

of California homeowners to bring their units into compliance without fear of retroactive penalties or forced removal. 

2. Health and Safety as the Primary Standard 

The bill limits the reasons local agencies can use to deny permit applications. If a unit does not present a substantial health and safety risk under California’s health and safety standards, it must be eligible for permitting—even if it doesn’t meet other technical building code requirements from the time of its construction. 

This is a major shift from the old model, which allowed jurisdictions to reject ADUs for issues that had no bearing on the safety or livability of the space. 

3. Financial Relief for Homeowners 

Recognizing the financial burden that retroactive permitting can create, AB 2533 prohibits agencies from charging impact fees, connection fees, or capacity charges during the legalization process. This can amount to thousands of dollars in savings for homeowners who want to bring their ADUs up to code. 

4. Confidential, Third-Party Inspections 

Before initiating the legalization process, homeowners are allowed to obtain a confidential inspection by a licensed third-party contractor. This allows them to understand what health and safety upgrades might be necessary—without triggering code enforcement action. It provides a low-risk opportunity to make informed decisions before engaging with their local jurisdiction. 

5. Public Transparency Requirements 

To ensure homeowners are aware of the new legalization process, AB 2533 requires local governments to provide clear, accessible information online and in public offices. Agencies must post checklists, application forms, and instructions for ADU legalization—helping to remove one of the biggest historic barriers: a lack of clear guidance. 

Benefits for Homeowners 

AB 2533 represents a win-win for many California homeowners. For those who built unpermitted ADUs out of necessity—whether to house family, generate rental income, or respond to high housing costs—this law provides a second chance to bring those units into the fold legally. 

Legalization can: 

● Increase property values 

● Allow for lawful rentals and lease agreements 

● Enable refinancing or home equity loans

● Reduce the risk of fines, insurance issues, or future forced removal 

● Provide peace of mind knowing the unit meets safety standards 

Benefits for Renters 

From the tenant's perspective, the legalization of ADUs means more stable, secure housing. Renters living in unpermitted units often deal with uncertainty or poor living conditions due to the threat of code enforcement. Legalizing these units ensures they are safe and subject to basic tenant protections under California law. 

Moreover, it supports the state’s broader goal of increasing the availability of lower-cost rentals, especially in high-demand urban and suburban areas where new multifamily construction is difficult or controversial. 

A Challenge for Local Governments—and an Opportunity 

While AB 2533 imposes new requirements on cities and counties, it also offers them a valuable tool to address the housing shortage. Many jurisdictions know they have hundreds—sometimes thousands—of unpermitted ADUs within their boundaries. Legalizing these units helps them meet their housing targets, including their RHNA (Regional Housing Needs Allocation) goals, and gives them better data for planning infrastructure and services. 

However, successful implementation will require commitment. Local governments must update ordinances, retrain staff, simplify permitting procedures, and actively inform the public about the new process. The law nullifies any local ordinances that conflict with AB 2533, meaning jurisdictions cannot adopt rules that undermine the state’s intent. 

Next Steps for Homeowners 

If you’re a homeowner with an unpermitted ADU built before 2020, AB 2533 gives you a clear path forward. Here’s how to get started: 

1. Check Eligibility – Confirm your unit was built before January 1, 2020 and has not been subject to recent code enforcement action.

2. Hire a Licensed Inspector – Consider a confidential inspection to assess whether the unit meets health and safety requirements. 

3. Contact Your City or County – Visit your local agency’s website or office for ADU legalization checklists and permit application guidance. 

4. Plan for Repairs or Upgrades – Focus on resolving any identified safety issues, such as fire alarms, ventilation, or emergency egress. 

5. Apply for a Permit – Submit your application, take advantage of the fee waivers, and follow through with any necessary inspections or adjustments. 

Looking Ahead 

AB 2533 is part of a broader, ongoing legislative movement to make ADU construction and legalization simpler, cheaper, and more accessible. Alongside other 2025 updates to the state’s ADU handbook and related bills (like AB 434 and AB 976), the state is sending a clear message: ADUs are not just tolerated—they are encouraged. 

The success of AB 2533 will depend on cooperation between homeowners, local governments, and the construction industry. But if fully implemented, this law could result in thousands of new legal housing units across California—units that already exist, but until now, have remained in legal limbo.

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