AB 1033 in San Diego: How the New ADU Condo Law Works in the City and Unincorporated County

Short answer: As of 2026, AB 1033 is live in both the City of San Diego (effective August 22, 2025) and the unincorporated areas of San Diego County (effective April 4, 2026). Qualifying homeowners can now subdivide a primary home and its accessory dwelling unit (ADU) into two condominium units and sell the ADU separately. It is not automatic, it is not cheap, and it is not the same thing as SB 9.

This guide explains how the law works in each jurisdiction, where unincorporated communities run into practical limits, and how AB 1033 stacks up against a standard ADU rental and against SB 9 lot splits.

Key Takeaways

• AB 1033 is a local opt-in law. It only works in cities or counties that have passed an enabling ordinance. The City of San Diego and the County of San Diego have both opted in.
• City of San Diego: Adopted June 18, 2025, effective August 22, 2025. San Diego was the first jurisdiction in the county to opt in.
• Unincorporated San Diego County: Board of Supervisors adopted on March 4, 2026; effective April 4, 2026, under Section 6156.x of the County Zoning Ordinance.
• The ADU does not become a separate lot. It becomes a separate condominium unit on the same parcel.
• An HOA is mandatory, even on a two-unit property. Utilities must be separately metered. Every existing lender must consent before the condo map is recorded.
• JADUs (Junior ADUs) cannot be sold separately under either jurisdiction.
• SB 9 is a different tool. SB 9 splits the lot into two parcels and can yield up to four fee-simple units. AB 1033 keeps one lot and creates condominiums.

What AB 1033 Actually Does

California Assembly Bill 1033 (signed into law in 2023) amended the state’s ADU statute to let local governments authorize the separate sale of an ADU as a condominium. Before AB 1033, a homeowner who built an ADU could rent it but not sell it independently of the main house.

AB 1033 does not:

• Increase the number of units allowed on a lot.
• Override local zoning, setbacks, parking, or design rules.
• Apply automatically. Each city and county must adopt its own ordinance.

It does:

• Allow a primary home and its ADU to be re-titled as two condominium units.
• Permit each unit to have its own deed, its own mortgage, its own property tax bill.
• Require an HOA to govern shared land, utilities, insurance, and maintenance.

Timeline: How San Diego Got Here

AB 1033 in the City of San Diego

The City of San Diego folded AB 1033 into a larger 25-item ADU reform package. Inside city limits, a homeowner with a permitted ADU can apply to:

1. Subdivide the property into a primary-residence condominium unit and an ADU condominium unit.
2. Record a condominium plan with the County Recorder after obtaining lender consent and forming an HOA.
3. Sell either unit independently.

The city did not adopt this in isolation. The same June 2025 ordinance also relaxed several ADU rules in transit-priority areas, which means homeowners in eligible neighborhoods may be building ADUs explicitly for AB 1033 condo conversion. Coastal-zone parcels still require coordination with the California Coastal Commission’s permitting framework where applicable.

AB 1033 in Unincorporated San Diego County

A blunt note up front: the County adopted one ordinance that applies across all unincorporated communities. There is no separate AB 1033 rule for Alpine versus Ramona versus Fallbrook. Trying to write a section on “each unincorporated area” overstates how granular the law is. What actually varies, community by community, is the underlying zoning, infrastructure, and overlay rules that any ADU project has to clear before AB 1033 even enters the picture.

Below are the practical buckets that matter.

The Countywide Rule (Section 6156.x)

For any ADU in unincorporated San Diego County to be sold separately, the project must:

• Be a permitted ADU on a parcel that meets ADU eligibility under state and county law. JADUs are excluded.
• Receive Tentative Parcel Map or Tentative Map approval through Planning & Development Services. AB 1033 does not bypass the Subdivision Map Act.
• Demonstrate separate metered utility service for water, sewer or septic, gas, and electricity.
• Establish an HOA with recorded CC&Rs governing the shared parcel, insurance, and maintenance.
• Obtain written consent from every lienholder (mortgage, HELOC, deed of trust) before the condominium plan is recorded.
• Comply with the existing zoning, setbacks, height, and design standards for the underlying zone.

Coastal Unincorporated Areas

Most of San Diego County’s coastline is inside the incorporated cities of San Diego, Coronado, Imperial Beach, Del Mar, Solana Beach, Encinitas, Carlsbad, and Oceanside, but unincorporated pockets fall within the Coastal Overlay Zone. Projects in these areas may need a Coastal Development Permit. Common AB 1033 trip-wires:

• Within 50 feet of a bluff edge.
• Within 300 feet of the mean high tide line.
• Vegetation removal within 100 feet of a bluff.

Outside those buffers, an ADU may qualify for a CDP exemption, but the AB 1033 condominium conversion still requires the underlying subdivision approvals.

Fire-Prone Rural Communities

Communities such as Alpine, Julian, Fallbrook, Valley Center, Jamul, Ramona, Pine Valley, Pala, Potrero, Boulevard, Campo, Descanso, Mt. Laguna, and Warner Springs fall in Very High Fire Hazard Severity Zones or are served by limited fire infrastructure (the County Fire Authority covers ~1.5 million acres with 35 stations). AB 1033 itself does not change fire rules, but expect:

• Wildland-Urban Interface (WUI) building code requirements (ignition-resistant materials, ember-resistant venting).
• Defensible space and fuel modification requirements.
• Driveway and access standards for emergency apparatus, which may complicate adding a separately deeded ADU at the end of a long shared driveway.
• Fire-flow water requirements that can be hard to satisfy on parcels relying on wells or small water districts.

This is where rural concerns at the December 2025 Planning Commission hearing focused. The Board ultimately adopted the ordinance countywide, but practical eligibility in these areas is constrained by the underlying infrastructure rather than by AB 1033.

Septic and Well Communities

Most unincorporated parcels outside village cores rely on on-site septic systems and well water or small water districts. AB 1033 requires separately metered utilities, which is more complicated on:

• Shared septic systems. The Department of Environmental Health (DEH) must sign off on capacity and leach-field separation.
• Private wells. Separate water service for the ADU condo typically means either a second well, a separately metered tap from the existing well with allocation language in the CC&Rs, or connection to a water district where available.
• Properties in Valley Center, Ramona, Alpine, Pauma Valley, Bonsall, and similar rural areas frequently fall into this category.

Village-Zoned Communities

The County applies customized zoning to Fallbrook Village and the Ramona Village Center. These village zones have their own form-based or character-driven standards. AB 1033 conversions in these areas need to satisfy the village-specific design rules before the subdivision map can be approved.

Tribal-Adjacent and Reservation-Checkerboard Areas

Parcels near or interspersed with tribal land (parts of Pala, Pauma, Rincon, Santa Ysabel, Campo, La Jolla, San Pasqual, Los Coyotes, Manzanita, Mesa Grande, Sycuan, Viejas, and other reservations) can have unique utility, access, and jurisdictional considerations. AB 1033 does not change federal-tribal jurisdiction. If your parcel borders or is interlaced with reservation land, talk to PDS and a real-estate attorney before assuming conversion is straightforward.

Communities Where AB 1033 Is Most Workable Today

The conversion math is easiest where infrastructure is already urbanized: Spring Valley, La Presa, Lakeside, Bonita-Sunnyside, Crest, Dehesa-Granite Hills, parts of Casa de Oro-Mount Helix, and the unincorporated areas bordering Lemon Grove and El Cajon. These areas tend to have public water and sewer, smaller parcels, and zoning consistent with attached or detached ADUs already in place.

AB 1033 vs. a Standard ADU: Pros and Cons

The honest comparison is not “AB 1033 is better than a regular ADU.” It is “what do you actually want this property to do?”

Pros of AB 1033 (vs. keeping the ADU as a rental)

• Equity release without selling the main house. You can monetize the ADU’s value as a one-time sale rather than a long monthly cash flow.
• Multigenerational ownership. A parent can deed a unit to an adult child, or vice versa, with cleaner ownership lines than a rental arrangement.
• Affordable for-sale housing supply. ADU condos generally come to market at lower price points than detached single-family homes, broadening the buyer pool.
• Independent financing. Each unit can carry its own mortgage, which can be useful for estate planning.

Cons of AB 1033 (vs. keeping the ADU as a rental)

• HOA mandatory, even for two units. That means CC&Rs, reserves, insurance, annual meetings, and recurring dues — for a 2-door HOA. Many HOA-management firms will not take on a project this small, which leaves the owners to self-manage.
• Lender consent is a real obstacle. Existing mortgage holders can refuse consent, condition it on a refinance, or demand new loan terms. A 3% pandemic-era mortgage can become very expensive to “unlock” for an AB 1033 conversion.
• Subdivision Map Act costs. Tentative map, surveying, engineering, legal — realistic budgets often run $25,000–$75,000+ on top of any utility separation work.
• Property-value question. Real-estate practitioners are split on whether converted ADU condos appraise at the same per-square-foot value as comparable detached units. Resale comps for AB 1033 condos are still thin.
• Loss of rental cash flow. A sold ADU stops producing monthly rent. Run the numbers against a 10–15 year hold horizon.
• Tax implications. A condo conversion can trigger reassessment of the new condominium under Proposition 13 rules and may have capital-gains consequences. Talk to a CPA.
• You cannot un-do it easily. Once the condo plan is recorded and sold, you have a permanent HOA neighbor on your parcel.

When a Plain Rental ADU Beats AB 1033

If your goals are recurring income, simple management, full control of the parcel, and the option to move family in and out, a standard ADU is almost always the cleaner answer. AB 1033 makes the most sense when the goal is liquidity — converting trapped equity into cash without leaving the house.

SB 9 vs. AB 1033: Different Tools, Different Outcomes

SB 9 (effective 2022) and AB 1033 are often discussed in the same breath. They are not substitutes. They solve different problems.

The core difference: SB 9 changes the land. AB 1033 changes the ownership structure on existing land. If you want two real lots that can each be developed and sold, SB 9. If you already have an ADU and want to sell it without selling the main house, AB 1033.

Why they are sometimes confused: Both came out of California’s housing-supply push, both create a path from one home to multiple ownerships, and both are local-implementation-dependent in practice (SB 9 is technically statewide, but cities have been slow and procedurally restrictive).

Eligibility Checklist (Unincorporated San Diego County)

Before you spend money on architects or surveyors, walk through this list:

• The ADU is permitted, built to code, and has a certificate of occupancy.
• The ADU is not a JADU.
• The parcel can support separate metered water, sewer/septic, gas, and electricity for both units.
• You have current payoff statements and contact information for every lienholder.
• The parcel is not in a Very High Fire Hazard Severity Zone with unresolved access/water-supply issues — or, if it is, you have a path to compliance.
• If the parcel is in the Coastal Overlay Zone, you have analyzed CDP exposure.
• You have budgeted realistically for Tentative Parcel Map costs, HOA formation, attorney fees, and DEH review (if on septic).
• You have a CPA opinion on reassessment and capital-gains exposure.

If you cannot check all of these, AB 1033 may not yet be the right move on your specific parcel.

Frequently Asked Questions

Is AB 1033 in effect in San Diego right now?

Yes. The City of San Diego ordinance has been in effect since August 22, 2025. The unincorporated San Diego County ordinance has been in effect since April 4, 2026.

Can I sell my ADU without my lender’s permission?

No. AB 1033 requires written consent from every lienholder before the condominium plan can be recorded. This is a non-negotiable statutory requirement, not a local rule.

Can I convert a JADU into a sellable condo?

No. Junior ADUs are explicitly excluded under both the City and County ordinances and under state law.

Do I have to form an HOA for just two units?

Yes. AB 1033 requires an HOA structure to govern shared land, common-area maintenance, and insurance, regardless of unit count.

Does AB 1033 raise my property taxes?

Likely yes on the newly created condominium unit, which can be reassessed at fair market value when transferred to a new owner. The primary unit’s Prop 13 base year may be preserved. Talk to a CPA and the Assessor’s office before relying on any specific outcome.

Is AB 1033 a replacement for SB 9?

No. SB 9 splits a lot. AB 1033 condominium-izes a lot. They can theoretically be combined in narrow cases, but the use cases are different.

Which San Diego unincorporated communities benefit the most from AB 1033?

In practice, communities with public water/sewer and smaller lots — Spring Valley, La Presa, Lakeside, Bonita-Sunnyside, and similar urbanized unincorporated pockets — face the fewest infrastructure hurdles. Rural fire-zone communities can still use AB 1033 but face additional WUI, water-supply, and access-compliance steps.

Can I build a new ADU specifically to sell it under AB 1033?

Yes, in both the City and County. There is no requirement that the ADU pre-date the ordinance. However, the financial case has to account for full construction cost plus the subdivision and HOA overhead.

Bottom Line

AB 1033 is real, it is in effect in San Diego, and it does what its supporters claim: it gives ADU owners a path to sell. It is also expensive, paperwork-heavy, lender-gated, and HOA-burdened. For some owners — especially those sitting on substantial equity in a high-cost neighborhood — it is a meaningful financial tool. For others, particularly those happy with rental cash flow or sitting on a sub-4% mortgage they do not want to disturb, the standard ADU remains the better play.

The honest framing: AB 1033 is a liquidity law, not a density law. Treat it accordingly.

Sources and Further Reading

• San Diego County Planning & Development Services — ADU Zoning Ordinance Amendment
• San Diego County — Guidance for Separate Sale of ADUs under AB 1033 (PDF, April 3, 2026)
• City of San Diego — City Council Adopts Reforms to Accessory Dwelling Unit Program
• SANDAG — AB 1033: Permitting Separate Sale or Conveyance of ADUs (PDF)
• San Diego County — Housing Laws in Action
• California HCD — SB 9 Fact Sheet (PDF)
• Village News — Ordinance amendment including separate sale of ADUs adopted by Board of Supervisors

Legal Disclaimer

This article is provided for general informational purposes only and does not constitute legal, financial, tax, real estate, or land-use advice. The contents reflect publicly available information as of May 16, 2026, and AB 1033 implementation, San Diego City and County ordinances, fees, processing times, and eligibility standards may change without notice. Application of AB 1033, SB 9, the Subdivision Map Act, the California Coastal Act, fire-safety codes, environmental health requirements, and federal lending rules to any specific property depends on facts unique to that property and its current ownership, financing, and zoning status. Reading this article does not create an attorney-client, broker-client, or fiduciary relationship. Before taking any action — including but not limited to applying for a Tentative Parcel Map, entering into a condominium conversion, requesting lender consent, forming a homeowners association, or relying on any tax outcome described above — you should consult a licensed California real estate attorney, a licensed real estate broker familiar with San Diego ADU and condominium law, a certified public accountant, and the relevant city or county planning department. The author and publisher disclaim any liability arising from reliance on the contents of this article.