For most of California's history, an accessory dwelling unit has been legally tied to the main house it sits behind. You could rent it out, but you couldn't sell it separately, even though it has its own kitchen, its own bathroom, and its own front door. That changed for a small number of California homeowners in 2026, and San Diego County is one of only three places in the state where it's actually happening.
What Is AB 1033?
Assembly Bill 1033 is a California state law, originally passed in 2023, that allows a local city or county to opt in to a new rule: letting a homeowner subdivide their property so the main house and the ADU can be sold as two separate condominium units, each with its own owner. The state law only creates the option. Nothing changes until a specific city or county government votes to adopt it locally.
That local opt-in step is why AB 1033 sat mostly theoretical for the first couple of years after it passed. A homeowner in a jurisdiction that hadn't adopted it couldn't do anything differently than before.
San Diego County Voted to Adopt It in March 2026
The San Diego County Board of Supervisors voted to adopt AB 1033 on March 4, 2026, with the new rule taking effect on April 4, 2026. As of that date, San Diego County is one of only three jurisdictions in the entire state of California that has opted in, alongside San Jose and Santa Monica. That makes this a genuinely uncommon option right now, not something available to most California homeowners.
How the Separate-Sale Process Actually Works
Selling an ADU separately isn't as simple as putting up two "for sale" signs. The county's guidance describes a real subdivision process, not a paperwork formality:
- Tentative Parcel Map or Tentative Map application: the county has to approve splitting the property on paper before it can be split in ownership
- Condominium documentation: the two units get organized under a condominium structure, similar to how a duplex or townhome complex is set up, with shared elements (like the land itself) defined separately from what each owner exclusively owns
- Separate Assessor's Parcel Numbers (APNs): each unit needs its own APN so it can be taxed, financed, and sold independently
- Primary home and ADU established as separate ownership interests: once this is complete, the main house and the ADU can have two different owners, two different mortgages, and two different sets of property taxes
One important exception: Junior ADUs (JADUs) are not eligible for separate sale. A JADU is a smaller conversion within the existing footprint of the home, typically under 500 square feet, and current rules require it to stay part of the primary residence. Only a full ADU, generally a detached or attached unit with its own permitted living space, qualifies.
What's Still Being Finalized
San Diego County's ordinance took effect in April 2026, but not every detail was locked down on day one. Additional parameters, including owner-occupancy requirements and a first right of refusal for existing tenants, were still being worked out as of this writing, with a target date of July 2, 2026 for those pieces to be finalized. If you're considering this path, it's worth checking directly with the county for the current status of these requirements rather than assuming the rules that applied in April still apply exactly as written today.
What This Means If You're Planning an ADU Project
For homeowners in qualifying unincorporated areas, this opens a genuinely new option: building an ADU with the possibility of eventually selling it as its own unit, rather than only ever renting it out or keeping it as a family-use space. That changes the math on an ADU project for some homeowners, since it's no longer purely a rental-income or multigenerational-living decision. It can also be a way to help a family member get into a starter home on the same lot without needing a second mortgage on a second piece of land.
It's also a meaningfully bigger legal and financial undertaking than a standard ADU build. Subdividing a property into condominium interests involves real estate, title, and often tax implications well outside general contracting. This is a case where working with a real estate attorney or the county's planning office directly, alongside whichever contractor is handling the physical construction, is worth the extra step before committing to the plan.
Frequently Asked Questions
Does AB 1033 apply to the whole City of San Diego, or just certain areas?
Just certain areas. San Diego County's adoption of AB 1033 applies specifically to unincorporated parts of the county, communities like Ramona, Lakeside, Fallbrook, and similar areas governed directly by the county. The City of San Diego itself has not adopted this ordinance, so a property inside city limits doesn't qualify under this specific rule.
What exactly is AB 1033?
It's a California state law that gives local cities and counties the option to allow homeowners to subdivide a property so the main house and an ADU can be sold separately as condominium units, each with its own owner. The state law only creates the option. Each city or county has to separately vote to adopt it before it applies locally.
Can I sell an ADU I already built, or does this only apply to new construction?
The county's guidance describes this as a subdivision and condominium-conversion process, which is generally available for qualifying existing ADUs as well as new ones, provided the property is in an eligible unincorporated area and the ADU meets the requirements (including not being a Junior ADU). Confirm your specific situation with San Diego County Planning & Development Services, since eligibility depends on the details of your existing permit and property.
What is a Junior ADU, and why isn't it eligible?
A Junior ADU (JADU) is a smaller, more limited conversion, generally created within the existing walls of the primary home rather than as a separate structure, and typically capped around 500 square feet. Current rules keep JADUs tied to the primary residence rather than allowing them to become a separately owned unit, unlike a full ADU.
Do I need a real estate attorney to do this?
Working with a real estate attorney is worth strongly considering. Subdividing a property into separate condominium ownership interests involves title, financing, and tax considerations that go beyond what a general contractor or the county's building department typically handles. Wrkbid's role is connecting you with contractors for the physical construction, not providing legal or real estate guidance on the ownership structure itself.
How is this different from just renting out my ADU?
Renting an ADU keeps the entire property, main house and ADU, under one owner and one title. Selling under AB 1033 actually splits ownership: the ADU becomes its own condominium unit with its own owner, separate from whoever owns the main house. That's a fundamentally different, more permanent decision than a rental arrangement.
When exactly did this take effect in San Diego County?
The Board of Supervisors voted to adopt AB 1033 on March 4, 2026, with the ordinance taking effect April 4, 2026. Some related details, including owner-occupancy requirements and tenant right-of-first-refusal provisions, were still being finalized as of this writing, with a target date of July 2, 2026.
What other California cities allow this?
As of April 2026, only three jurisdictions statewide have opted in to AB 1033's separate-sale provisions: San Jose, Santa Monica, and unincorporated San Diego County. Most California cities and counties have not adopted this option, so it's worth checking current status directly if you're considering a property outside these three areas.