For decades the answer was simple: an ADU is part of your property, and it sells with the house. AB 1033 changed that, but the local rules now depend on exactly where the property is located. In the City of San Diego outside the Coastal Overlay Zone, the City’s AB 1033 condominium-sale rules became effective August 22, 2025. The City’s current guidance says the 2025 amendment has not yet taken effect within the Coastal Overlay Zone, so coastal properties should confirm the current rules with the City before planning around a separate sale. In unincorporated San Diego County, AB 1033 implementation became effective April 4, 2026, with additional local sale requirements effective September 18, 2026.

By Daniel Dechner, IL Total Design & Build — design, permit & build under one roof, San Diego  CSLB #1058676  Last updated: October 2026

The 60-second version

What AB 1033 actually did

Before AB 1033, California law was blunt: an ADU could not be sold or otherwise conveyed separately from the primary residence. You could build one, rent it out, house family in it — but the day you sold, it went with the house. AB 1033 gave every city and county the option to lift that restriction by adopting a local ordinance that treats the ADU and the primary home like condominium units. That word "option" matters. AB 1033 did nothing on its own. Each jurisdiction has to opt in, and each one writes its own rules. That is why the answer to "can I sell my ADU?" depends on the local jurisdiction and, within the City of San Diego, whether the property is inside the Coastal Overlay Zone.

Where you stand in San Diego, jurisdiction by jurisdiction

AB 1033 separate-sale status in the San Diego region (October 2026)

Jurisdiction	Can you sell an ADU separately?	Notes
City of San Diego	Yes outside the Coastal Overlay Zone — effective August 22, 2025	The City’s 2025 AB 1033 ordinance is effective outside the Coastal Overlay Zone. The City’s current guidance says the amendment has not yet taken effect within the Coastal Overlay Zone, so coastal properties should confirm the current applicable rules before relying on separate sale.
Unincorporated San Diego County	Yes — since April 4, 2026	County AB 1033 program effective April 4, 2026. Additional owner-occupancy, right-of-first-refusal, and public-marketing requirements became effective September 18, 2026.
Encinitas, Carlsbad, Oceanside & other independent cities	Varies — confirm locally	Each city must adopt its own AB 1033 ordinance; status changes frequently. We verify your city's current position as part of feasibility

If your property is in a North County city or another incorporated jurisdiction, do not assume AB 1033 separate-sale rules apply. Each city controls its own local implementation. If future separate sale matters to you, confirm the current rules for your jurisdiction and discuss possible condominium-conversion considerations during the ADU design process.

How the conversion actually works

This is a condominium conversion under the Subdivision Map Act — the same legal machinery used when an apartment building converts to condos, scaled down to a house and its ADU. The land stays one lot; ownership of the structures is divided. Here's the honest version of what it takes:

1. Tentative parcel map A licensed surveyor or civil engineer prepares a condominium map application for the jurisdiction. This is a real subdivision-level entitlement, not a form at the permit counter.
2. Utility coordination Creating an ADU condominium requires coordination with the utility providers serving the property. Providers must be notified of the condominium creation and separate conveyance, and separate connections or metering may be required depending on the utility, jurisdiction, existing service, and project. Planning possible utility separation during ADU design can be much easier than retrofitting a finished property later.
3. Lender consent, in writing Every lender, deed-of-trust holder, and lienholder on the property must consent before a condominium map can be recorded. Lenders can say no, or attach conditions. If you have an existing mortgage, this is usually the single hardest step.
4. CC&Rs and a two-unit HOA The units will share land, so recorded covenants govern maintenance, insurance, access, and cost-sharing — effectively a very small homeowners association between you and your future buyer.
5. Separate ownership and sale Once the condominium plan and required subdivision documents are recorded, the units can be established as separate ownership interests and conveyed separately. Parcel identification, assessment, and property-tax treatment should be confirmed with the County Assessor for the specific conversion.

A condominium conversion can be a lengthy process. Timing depends on subdivision mapping, lender consent, utility coordination, legal documents, agency review, final inspections, and recordation. Treat it as a long-term ownership strategy rather than a quick way to sell an ADU. Planning for possible conversion during design and construction can also be easier than retrofitting a finished property later.

Build now, decide later: the condo-ready ADU

Here's the practical takeaway for anyone planning an ADU in San Diego in 2026. During ADU design, you do not have to commit to selling the unit later. The goal is to avoid making future conversion harder than it needs to be. Utility routes, access, building placement, and other site decisions are much easier to think through before construction than after the property is finished:

What "condo-ready" means during design and construction

Decision	Why it matters for separate sale
Plan utility separation and meter locations early	A separate sale may require additional utility coordination, connections, or metering depending on the provider and property. Planning space and routes during construction is usually easier than retrofitting them after the site is finished.
Independent access and address	Clear independent access can make future separate ownership more practical, but final condominium eligibility still depends on the applicable legal, mapping, and agency requirements.
Fire separation & building placement	Building placement and required fire separation can affect mapping, access, insurance, and agency review. These design choices do not by themselves establish legal eligibility for condominium conversion.
Full-function layout	A future buyer's lender appraises the ADU as a standalone home — full kitchen, laundry, and storage all support value

We now walk every design client through this decision at feasibility: is this ADU family housing, a rental, or a potential asset you might sell? The answer may affect utility planning, access, building placement, and other site decisions that are easier to address during design than after construction. It also interacts with your property tax picture, since a converted ADU gets its own assessment, and with how you finance the build, since the lender you choose today is the lender whose consent you'll need tomorrow.

AB 1033 condo conversion vs. an SB 9 lot split

Homeowners researching this often run into SB 9 and assume it's the same thing. It isn't, and the right tool depends on your lot and your goal:

Two ways to create a sellable second home on one property

	AB 1033 (ADU condo conversion)	SB 9 (urban lot split)
What divides	Ownership of the units; the land stays one lot	The land itself splits into two lots
Where it works	City of San Diego outside the Coastal Overlay Zone and unincorporated San Diego County, subject to the applicable local rules	Single-family zones statewide, subject to SB 9 criteria
Ongoing relationship	Shared CC&Rs and a small HOA with the buyer	Clean separation — two independent lots
Owner-occupancy	City of San Diego outside Coastal Overlay Zone: 30-day initial owner-occupant marketing requirement. Unincorporated County: buyer or family-member primary-residence affidavit for at least 1 year, plus ROFR and 30-day public-marketing requirements.	Three-year owner-occupancy affidavit required for the split
Typical fit	Lots that can't split, or owners who want to keep the land whole	Larger lots that meet split criteria and owners wanting a full exit

We compared the two paths in more depth in SB9 vs. ADU. The short version: AB 1033 can create a separate-sale path for some San Diego properties that do not qualify for an SB 9 lot split.

What this does to the math on building an ADU

Until now, an ADU's return came from two places: rent and added property value. AB 1033 can add another long-term option in jurisdictions where separate condominium sale is permitted and the property meets the conversion requirements. A detached ADU that may qualify for future separate condominium sale gives an owner a different set of long-term options than an ADU that must remain part of the primary property. It changes the conversation for the three kinds of clients we see most: families building for aging parents (the unit can eventually be sold rather than sitting empty), rental investors (an exit option de-risks the hold), and empty-nesters downsizing into the ADU (who could one day sell the unit they're not living in — in either direction). We'd stop short of the hype you'll see elsewhere. A condominium conversion involves mapping, lender consent, legal documents, agency review, and recordation, and it does not guarantee a particular resale value. In unincorporated San Diego County, separate-sale projects now also have to account for the County requirements that took effect September 18, 2026, including the right of first refusal, buyer occupancy affidavit, and public-marketing period. Budget-wise, the ADU build itself still depends on the project scope — our 2026 cost guide remains a useful starting point, while any condo-conversion planning should be priced for the specific property.

AB 1033 FAQ

Can I sell my ADU separately from my house in San Diego?

In the City of San Diego outside the Coastal Overlay Zone, separate condominium sale is permitted under the City's AB 1033 implementation. It is also permitted in unincorporated San Diego County under the County's program. For properties in the City's Coastal Overlay Zone and in other incorporated cities in San Diego County, verify the current local rules before relying on a separate sale.

Is an AB 1033 conversion the same as splitting my lot?

No. Your land stays one lot. The conversion divides ownership of the structures through a condominium arrangement, so the unit owners share the lot under recorded common-interest documents. An SB 9 urban lot split, by contrast, divides the land itself into two separate lots and has its own eligibility rules.

What does it take to convert an ADU to a sellable condo?

The process can include subdivision or condominium mapping, final inspection and required building documentation, written consent from lienholders, CC&Rs and other common-interest documents, utility-provider coordination, agency review, and recordation. The exact requirements depend on the jurisdiction and property. A condominium conversion can be lengthy, so it should be treated as a long-term ownership process rather than a quick sale strategy.

Do I need my mortgage lender's permission to sell my ADU?

Yes. Written consent from each lienholder or deed-of-trust holder is required before the subdivision map or condominium plan can be recorded. A lender can refuse consent or impose conditions. If you are financing the ADU build, the loan you choose can affect the consent process later.

Should I build my ADU differently if I might sell it someday?

Planning early can help. Utility providers must be notified as part of the condominium process, and separate connections or metering may be required depending on the provider, jurisdiction, existing service, and project. Planning possible utility separation, access, building placement, and other site details during design is usually easier than retrofitting them later, but those choices do not guarantee legal eligibility for condominium conversion.

Will the ADU have its own property taxes after conversion?

Once a condominium plan is recorded and the units are established as separate ownership interests, the County Assessor may issue separate parcel numbers and assess the units accordingly. Before conversion, a permitted ADU generally affects the assessment based on new construction rather than automatically reassessing the entire primary home. Property-tax treatment should be confirmed with the County Assessor for the specific condominium conversion.

What changed for separate ADU sales in unincorporated San Diego County in September 2026?

Effective September 18, 2026, the County added a right-of-first-refusal requirement, a buyer or family-member primary-residence affidavit for at least one year, and a 30-day public-marketing requirement for ADU condominium sales.

Keep exploring

Not legal advice. This page summarizes AB 1033 (2023) and its local implementation in the San Diego region as we understand it for general informational purposes. Condominium conversion involves subdivision mapping, title, and lending questions that require a licensed surveyor, real-estate attorney, and your lender — we design and build; we coordinate with those professionals but don't replace them. Rules change frequently and local implementation varies; we verify current requirements for your specific jurisdiction and lot before design. Prepared by IL Total Design & Build (CSLB #1058676). Last updated October 2026.

Sources: California Government Code §66342; City of San Diego ADU/JADU regulations and Information Bulletin 400; City of San Diego 2025 ADU/JADU ordinance amendments; County of San Diego ADU Zoning Ordinance Amendment / Separate Sale of ADUs; San Diego County Zoning Ordinance §6156.x.D; County ADU Condo Guidance & Checklist updated September 18, 2026.