What SB 9 Allows: The Urban Lot Split Law
For most of modern California zoning history, ADUs could not be sold separately from the primary dwelling. If you built a backyard cottage, it was legally tied to your main house — you could rent it but not sell it as an independent piece of property. California Senate Bill 9 (SB 9), effective January 1, 2022, changed this in a significant way. SB 9 is officially the California Housing Opportunity and More Efficiency (HOME) Act. It created two related rights: the right to split a qualifying single-family lot into two parcels, and the right to build two units on a single-family lot without a lot split. The lot split provision is what makes separate ADU sale possible. Under California Government Code as amended by SB 9, a homeowner may apply for a ministerial lot split of a single-family parcel. Once the lot is split into two separate legal parcels, those parcels can be sold independently. If you build an ADU on one of the resulting parcels, that parcel — with its ADU — becomes a separate legal property that can be sold to a different buyer than the parcel with the primary dwelling. The stateSBILaw in California's data is clear: SB 9 (effective January 1, 2022) requires cities to ministerially approve splitting a single-family lot into two parcels where the original lot is at least 2,400 square feet and the resulting parcels are each at least 1,200 square feet. On each resulting parcel, the owner may build up to 2 units, for a total potential of 4 units on what was previously a single-family lot. The ministerial approval requirement is critical — cities cannot require discretionary review, design commission approval, or public hearings for qualifying SB 9 lot splits. The process is administrative, not political. SB 9 significantly expands what is possible on California single-family lots. A typical single-family home that previously generated a single resale transaction can now generate two separate property sales. Understanding the specific eligibility requirements is essential before planning a project around this provision.
SB 9 Eligibility Requirements
SB 9's ministerial lot split approval applies to qualifying properties — not every California single-family lot is eligible. The eligibility rules were designed to focus the lot split right on urbanized areas where housing demand is highest while protecting environmentally sensitive areas and historic neighborhoods. The original lot must be in an urbanized area or urban cluster (as defined by the US Census Bureau). Rural single-family lots are not eligible for SB 9 lot splits. The original lot must be at least 2,400 square feet. This threshold exists to ensure the resulting parcels are large enough to be practical building sites. The resulting parcels must each be at least 1,200 square feet. After the split, neither parcel can be smaller than 1,200 square feet. In most urban California lots, this is a minimal constraint — many single-family lots are 5,000 to 8,000 square feet, resulting in two parcels of 2,500 to 4,000 square feet each. The property must be in a single-family residential zone. Multifamily zoned properties are not eligible for SB 9 lot splits (they have their own development pathways). The property must not be located in: a historic district or on a property designated as a historic landmark; a coastal zone subject to Coastal Act requirements; a high fire hazard severity zone; an earthquake fault zone; a special flood hazard area; or land identified for conservation or agricultural protection. The owner applying for the lot split must intend to occupy one of the resulting units as their primary residence for at least 3 years following the lot split approval. This owner-occupancy requirement was included to prevent speculative flipping of SB 9 lots — the law was designed for homeowners who want to add housing, not for investors buying properties solely to split and flip. In Los Angeles, San Francisco, San Diego, and San Jose, the vast majority of single-family lots in urbanized neighborhoods meet the basic size requirements for SB 9 eligibility, subject to the exclusions listed above.
The Lot Split Process Step by Step
Executing an SB 9 lot split in California involves several sequential steps. Understanding the process helps you plan timelines and costs accurately. Step 1: Confirm eligibility. Check your lot size, zone, and location relative to the SB 9 exclusions (historic district, coastal zone, high fire hazard zone, earthquake fault zone, floodplain). Use your city's online zoning map and parcel search to identify your current lot size, zone designation, and any overlay zones that might disqualify your parcel. Step 2: Hire a licensed land surveyor. A boundary survey of your existing lot is required before the split. The surveyor will identify existing property lines, easements, encroachments, and the most logical location for the new dividing line. Budget $3,000 to $8,000 for a boundary survey and lot split plat preparation in California. Step 3: Determine the split line. The most practical split is typically a straight line dividing the lot into a front parcel (with the existing primary dwelling) and a rear parcel (which will contain the ADU or new construction). In some cases, a side-by-side split may be more appropriate depending on lot shape, easements, and planned construction. Step 4: Prepare a tentative parcel map or lot merger and subdivision application. California's streamlined SB 9 process requires a parcel map rather than a full subdivision map. Your surveyor or a civil engineer prepares this document for submission to the planning or building department. Step 5: Submit for ministerial approval. The city must process your SB 9 lot split application ministerially — no public hearing, no design commission review. Processing time varies by city but should be faster than discretionary approvals. California cities that were processing SB 9 applications in 2022-2024 typically took 3-8 weeks for ministerial review. Step 6: Record the parcel map. After city approval, the parcel map must be recorded with the county recorder. Recording fees are typically $100 to $500. Once recorded, the two parcels are separate legal properties with separate APN (assessor parcel number) designations. Step 7: Develop each parcel. On each of the two resulting parcels, you may build up to 2 units by-right. This could mean building an ADU on the rear parcel while the existing primary dwelling remains on the front parcel. Step 8: Sell one or both parcels. Once separate parcels are recorded, each can be sold independently. Title insurance, escrow, and standard real estate transaction procedures apply to each parcel as a standalone property.
City Implementation: How LA, SF, and Other California Cities Handle SB 9
California cities are required to process SB 9 applications ministerially — they cannot ban SB 9 lot splits. However, cities do have some discretion in implementing objective standards for development on the resulting parcels. Here is how major California cities have approached SB 9 implementation. Los Angeles implemented SB 9 as required by state law. LADBS processes lot split applications and building permits for SB 9 projects. LA's community plan areas may apply objective design standards, but no discretionary review is allowed. Los Angeles's historic districts (HPOZs) and hillside areas are excluded from SB 9 eligibility per state law. Los Angeles also benefits from California's active ADU law — both parcels resulting from an SB 9 split can have a primary unit plus an ADU, potentially resulting in 4 total units. San Francisco implemented SB 9 as required, though SF's Zoning Code applies objective standards for new construction on SB 9 parcels. SF's many historic districts (California Register, National Register, Article 10/11 landmarks) are excluded from SB 9 eligibility per state law. Given SF's 47-square-mile geography and extensive landmark designations, a significant portion of SF's single-family housing stock is in eligible areas — particularly in the western and southern neighborhoods like West Portal, Forest Hill, Sunset, and Richmond Districts, where historic protections are less pervasive. San Diego offers a Standard ADU Plan Program that can be used in combination with SB 9 — a homeowner can split the lot and use a pre-approved plan for the ADU on the rear parcel, reducing design costs and review time. San Diego's extensive coastal zone creates SB 9 eligibility complications for coastal neighborhoods. San Jose implemented SB 9 as required. Silicon Valley's high property values make SB 9 lot splits financially attractive in San Jose — a buildable 2,000-square-foot rear parcel in San Jose might be worth $400,000 to $600,000 as a separate legal parcel. Sacramento implemented SB 9 as required. Sacramento is also enrolled in California's ADU financing programs (CalHFA ADU grants), potentially reducing costs for SB 9 + ADU combinations. Sacramento's older grid neighborhoods have regular rectangular lots well-suited to SB 9 front/rear splits.
Financial Considerations: Is an SB 9 Lot Split Worth It?
The financial case for an SB 9 lot split depends on your local real estate market, your lot's current value, the cost of any development on the resulting parcels, and your goals (rental income vs. land sale vs. development and sale). In high-value California markets, SB 9 lot splits can create significant financial value. Here is how the math typically works. A typical San Jose lot in a single-family neighborhood might be worth $800,000 to $1.5 million as a single parcel with one existing primary dwelling. After an SB 9 lot split, you have: Front parcel ($500,000-$900,000) with the existing primary dwelling. Rear parcel ($250,000-$500,000) as a vacant buildable lot with ADU by-right entitlement. The sum of the two parcels often exceeds the pre-split value — you have created value through subdivision, not just built something. The rear parcel can be sold vacant to a developer or builder who constructs their own ADU or small home, generating a land sale without construction costs or risk. Alternatively, you can develop the rear parcel yourself — building an ADU for rental income or for a family member — and benefit from the rent-paying unit without ever selling the parcel. In Sacramento, land values are lower than the Bay Area but the same analysis applies at a smaller scale. A Sacramento single-family lot worth $400,000 might split into a front parcel at $280,000 (existing home) and a rear parcel at $150,000-$180,000. The rear parcel sale alone can cover a significant portion of the original purchase price or renovation costs. Costs to factor in: land surveyor ($3,000-$8,000), lot split application fees ($500-$2,000), parcel map recording ($100-$500), attorney fees if easements or shared utility agreements are needed ($1,500-$5,000), and any development costs on the new parcel. Property taxes will be reassessed separately on each parcel after the split. This can increase total annual property taxes, though each parcel is assessed at its own fair market value. SB 9 applications must include owner intent to occupy — if you apply for a lot split and immediately sell both parcels, you may not meet the owner-occupancy intent requirement and the application could be challenged.
AB 1033: Selling ADUs as Condominiums
California's SB 9 is not the only pathway to separately selling an ADU. AB 1033 (2023) created a second mechanism: allowing ADUs to be sold separately as condominiums from the primary dwelling, in jurisdictions that adopt an enabling ordinance under AB 1033. AB 1033 allows local jurisdictions to optionally permit ADU condominiumization — the process of converting a single parcel with a primary dwelling and ADU into a condominium structure where the primary dwelling and ADU are each independently saleable as condominiums, without requiring a lot split. The advantage of AB 1033 over SB 9 is that it does not require a physical lot split or parcel map. The ADU and primary dwelling remain on the same legal parcel, but each unit is a separate legal interest (a condominium interest) that can be sold, mortgaged, and transferred independently. As of 2026, several California cities have begun exploring AB 1033 enabling ordinances. Los Angeles, San Jose, and other cities have been evaluating adoption. Check with your city planning department to determine if your city has adopted an AB 1033 ordinance authorizing ADU condominiumization. The AB 1033 process requires a recorded condominium plan (similar to a standard subdivision map for condominiums), CC&Rs (conditions, covenants, and restrictions) governing the relationship between the primary dwelling and ADU, and HOA or condominium association setup (typically minimal for a 2-unit condominium). Costs for AB 1033 condominiumization are typically lower than an SB 9 lot split because no parcel map is required. Attorney fees for CC&R drafting and condominium plan preparation are the primary additional costs, typically $3,000 to $8,000. AB 1033 provides the cleanest ownership structure for homeowners who want to keep a single, undivided lot while giving the ADU the ability to be independently financed and sold.
Other States With Lot Split Laws
California's SB 9 was the first comprehensive statewide residential lot split law, but other states have followed with their own mechanisms. Oregon and Washington have taken somewhat different approaches to achieving similar density goals. Oregon Senate Bill 458 (SB 458), effective July 1, 2022, requires Oregon cities that must allow middle housing under HB 2001 to also allow lot divisions for middle housing development. Oregon's approach is specifically tied to middle housing — duplexes, triplexes, cottage clusters — rather than ADUs specifically. If you build a duplex or cottage cluster on an Oregon lot under HB 2001, SB 458 allows you to divide the lot to create separate parcels for individual unit ownership. This enables fee-simple ownership of townhomes and duplexes that were previously only available as condominiums. Oregon's SB 458 is more of an ownership structure reform than a density tool — it makes middle housing more financeable (individual units can be mortgaged separately) without necessarily adding more units. Washington HB 1337 (2023) requires all Washington cities to allow 2 ADUs per single-family lot, but Washington does not have a statewide residential lot split law equivalent to California SB 9. Lot splits in Washington are governed by local subdivision codes — some Washington cities allow lot splits that could enable separate ADU sale under local programs, but there is no statewide right. Colorado HB 24-1175 (2024) requires ADUs per lot statewide but does not include a lot split provision. Texas has no statewide lot split law — local subdivision codes govern in all Texas cities. New York State has no lot split law — subdivision of land is governed by local zoning and planning boards under New York General City Law, Town Law, and Village Law. For homeowners looking to separately sell an ADU, California remains the national leader with both SB 9 (lot splits) and AB 1033 (ADU condominiumization) providing two distinct pathways.
Frequently Asked Questions
What is SB 9 and does it apply to my property?
SB 9 (effective January 1, 2022) is a California state law authorizing ministerial lot splits for qualifying single-family parcels. Your lot qualifies if it is: in an urbanized area, at least 2,400 sqft, in a single-family residential zone, not in a historic district, coastal zone, high fire hazard zone, earthquake fault zone, or floodplain. The owner must intend to occupy one resulting unit as a primary residence for 3 years.
Can I actually sell just the ADU and keep the main house?
Yes, via an SB 9 lot split. After a qualifying lot split creates two separate legal parcels, each parcel can be sold independently. You can build an ADU on the rear parcel and sell that parcel separately while keeping the front parcel with your primary dwelling. AB 1033 (2023) provides an alternative via ADU condominiumization in cities that adopt an enabling ordinance.
Do I have to live on the property to do an SB 9 lot split?
Yes. The owner applying for an SB 9 lot split must intend to occupy one of the resulting units as their primary residence for at least 3 years following approval. This requirement was included to prevent speculative lot splits. If you do not intend to occupy one of the units, an SB 9 lot split is not available to you.
What does AB 1033 allow?
AB 1033 (2023) allows local jurisdictions to optionally permit ADU condominiumization — selling an ADU separately from the primary dwelling as a condominium interest without requiring a physical lot split. The ADU and primary dwelling remain on the same parcel but become separately saleable condo units. Cities must adopt an enabling ordinance to allow this. As of 2026, several California cities are evaluating AB 1033 adoption.