California SB 9 in 2026: What Homeowners and Investors Can Build, and Where the Law Still Applies

California Senate Bill 9 lets most single-family lots hold up to four homes through a duplex, a lot split, or both. The law itself hasn’t changed much since 2022, but almost everything around it has: SB 450 tightened city approvals in 2025, courts are still deciding whether charter cities must comply, and parts of Los Angeles County’s burn areas now follow temporary exceptions.

This guide is current as of October 2026. It is written for homeowners and investors in Orange County, California, and applies statewide unless a section says otherwise.

[This content is for educational purposes only and does not constitute legal or financial advice. Always consult a licensed professional for your specific situation.]

What is California Senate Bill 9?

SB 9 is a California law, in effect since January 1, 2022, that requires cities to approve qualifying duplexes and lot splits on single-family lots without a public hearing. Used together, the two tools allow up to four homes where one stood.

SB 9 (Chapter 162, Statutes of 2021) added two sections to the Government Code: 65852.21 for two-unit developments and 66411.7 for urban lot splits. According to the state housing department, a city may deny an SB 9 application only if the project would have a specific, adverse impact on public health and safety or the physical environment that cannot be mitigated.

“Ministerial” approval means staff check your plans against written, objective standards. There is no hearing and no neighbor vote, and cities cannot require public notification or a hearing as a condition of approval.

SB 9 gives owners three paths:

1. Two-unit development: two primary homes on one lot, with no split.
2. Urban lot split: one lot divided into two parcels.
3. Both: a split, then up to two homes on each new parcel, for four total.

What did SB 450 change about SB 9 in 2025?

SB 450, effective January 1, 2025, requires cities to approve or deny a complete SB 9 application within 60 days, or it is deemed approved. It also bars cities from applying stricter SB 9-only standards than they apply to the rest of the zone.

Under SB 450, a city that misses the 60-day deadline has the application deemed approved, and a city that denies one must return a written list of every deficiency and how to fix it. The bill also removed the old rule that blocked projects requiring demolition of more than 25% of a home’s exterior walls.

UC Berkeley researchers note that SB 450 was a response to a pending court challenge and to low SB 9 production, and it prohibits non-uniform or more restrictive standards on SB 9 projects. In practical terms, cities can no longer enforce SB 9-specific requirements unless the statute specifically permits them.

The state housing department enforces floors that local rules cannot go below. Local standards cannot prevent two units of at least 800 square feet each, cannot prevent two 1,200-square-foot lots, and cannot require side or rear setbacks above four feet on upper floors. If your city adopted an SB 9 ordinance in 2022, parts of it may no longer be enforceable.

Does my lot qualify for SB 9?

Your lot qualifies if it is zoned single-family, sits in an urbanized area, and avoids SB 9’s exclusions. The main exclusions are historic properties, homes rented in the last three years, rent-controlled or deed-restricted housing, and specified hazardous or protected lands.

The full exclusion list from the state housing department covers affordable-covenant and rent-controlled housing, tenant-occupied homes from the past three years, parcels where units were removed under the Ellis Act in the last 15 years, historic resources, and environmentally sensitive or hazardous land. Cities publish local versions of that list; Costa Mesa’s, for example, names fire hazard zones, earthquake fault zones, flood zones, and hazardous waste sites.

One exclusion people miss is the HOA. In Costa Mesa’s words, SB 9 does not override HOA covenants, conditions, and restrictions, so an HOA can still prohibit SB 9 projects. Read your CC&Rs before you pay for a survey.

How big does my lot need to be to split it?

Each new lot must be at least 1,200 square feet, and the split can be no more uneven than 60/40. In practice, the original lot needs roughly 2,400 square feet.

The 1,200-square-foot floor comes from state guidance that local standards cannot prevent the creation of two 1,200-square-foot lots. The proportion rule appears in county guidance, which says the split must produce two lots of approximately equal size, at most 60/40.

Size is not the only physical test. Cities may require easements for utilities and access to the street, but they cannot demand right-of-way dedications, offsite improvements, or correction of nonconforming conditions. A deep lot or a corner lot usually solves the access problem; a narrow interior lot often does not.

Can I demolish my house, or a rental, and use SB 9?

You can demolish or alter an existing home under SB 9 unless it was occupied by a tenant in the last three years, or is rent-controlled or deed-restricted. SB 450 removed the old 25% exterior-wall limit.

The tenant rule is absolute: SB 9 does not apply if the project requires demolition or alteration of housing occupied by a tenant in the last three years. That is why the separate 25% wall rule became redundant and was dropped in 2025.

For investors, this means a house bought with a tenant in place is usually not an SB 9 project for its first three years. For a seller, it means a long-term rental may carry less SB 9 value than an owner-occupied home next door.

How many units can I build under SB 9?

Without a lot split, you can build two primary homes plus whatever ADU law allows. With a split, you get two homes on each new lot, and ADUs count toward that limit, for a maximum of four.

The state housing department puts it this way: on a lot that was not created by an SB 9 split, you can have up to two primary units plus ADUs as ADU law permits, such as two SB 9 units, an ADU, and a junior ADU. In a recent letter to Glendale, the department clarified that the two-unit cap that folds in ADUs applies only when a project uses the lot split.

On split lots, the rule tightens. You cannot build a duplex on a lot created through an SB 9 split and then add an ADU on top of it. Some cities, such as Costa Mesa in Orange County, cap every SB 9 scenario at four total units.

SB 9 path	Lot split?	Maximum homes	ADUs on top?	Owner occupancy (state law)	Usually fits
Two-unit development	No	2 primary units, plus ADUs allowed by ADU law (many cities cap at 4)	Yes	Not required	Owners adding rental income; investors keeping one parcel
Urban lot split only	Yes	2 lots, up to 2 homes each later	Counted within the 2-per-lot cap	3-year affidavit	Owners who want a separately sellable lot
Split + two units per lot	Yes	4	Counted within the cap	3-year affidavit	Owner-occupants building to rent or sell

The owner-occupancy column is explained in the next section, because it is the single biggest factor in who can actually use each path.

Do I have to live on the property to use SB 9?

Only if you split the lot. A lot split requires a signed affidavit that you will live in one of the units as your principal residence for three years; a two-unit project without a split carries no owner-occupancy requirement under SB 9.

The affidavit rule is spelled out by the state: an urban lot split applicant must commit to three years of principal residence from the date of approval, unless the applicant is a community land trust or qualified nonprofit. The three years run from approval, not from the end of construction.

Cities have tried to extend that requirement to duplexes. The state pushed back, finding that Laguna Beach had incorrectly imposed an owner-occupancy requirement on SB 9 developments, which SB 9 does not allow. If your city’s handout says otherwise, it may predate that guidance.

Can investors or LLCs use SB 9?

Investors can use the two-unit path, but in most cases not the lot split. Because the split requires a personal residency affidavit, cities such as Costa Mesa accept lot-split applications only from individuals and trusts, not LLCs or corporations.

Costa Mesa’s policy is explicit: only individual owners holding title in their own names or through a trust may apply for an urban lot split, and partnerships, LLCs, and corporations are excluded. The same document confirms that a two-unit development does not require the owner to live on the property.

The practical investor play is a two-unit project on a lot that has been owner-occupied or vacant for at least three years. A tenant-occupied purchase triggers the three-year tenant exclusion on any demolition or alteration.

Can I rent out SB 9 units or use them as short-term rentals?

You can rent SB 9 units, but only for terms longer than 30 days. Short-term vacation rentals are not allowed.

State guidance requires that any rental unit created under SB 9 be rented for terms greater than 30 days. Long-term rentals, family housing, and selling a unit on its own parcel all remain open.

Does SB 9 apply in my city right now?

SB 9 applies in every general-law city and in unincorporated county areas across California. Charter-city status is still in litigation, and parts of the Palisades, Eaton, and Altadena fire areas operate under temporary exceptions.

Three separate legal tracks determine whether SB 9 works at your address. Most Orange County homeowners are affected only by the first one, and only if they live in a charter city.

What’s happening with SB 9 in charter cities?

A 2024 trial ruling exempted five charter cities, but an appeals court sent the case back after SB 450 rewrote the law’s stated purpose. No court has exempted any other charter city, and even a plaintiff city has since adopted SB 9 rules.

The case began when Redondo Beach, Carson, Torrance, and Whittier sued in March 2022, with Del Mar joining in 2023, and the Attorney General appealed the trial court’s ruling in June 2024. The judge had found that SB 9’s stated goal, affordable housing, did not justify overriding charter-city control.

SB 450 added housing supply to that stated purpose. In an unpublished November 2025 decision, the Second District Court of Appeal sent the case back to the trial judge to reconsider in light of SB 450, while a separate appellate ruling upholding SB 9 in general-law cities still stands. As of mid-October 2026, no new trial-court ruling had been reported.

Meanwhile, Del Mar, one of the plaintiffs, adopted SB 9 regulations that took effect June 12, 2025, citing SB 450’s clarification that the law applies to charter cities. Several Orange County cities are charter cities, so confirm your city’s status and current SB 9 handout with its planning division.

Is SB 9 suspended in the Palisades and Eaton fire zones?

Executive Order N-32-25, signed July 30, 2025, let local governments suspend SB 9 in very high fire hazard severity zones inside the Palisades and Eaton fire boundaries. Malibu and Pasadena have since settled a lawsuit and reopened SB 9, while Los Angeles city and county remain in court.

The Governor’s order suspended Government Code sections 65852.21 and 66411.7 in state-designated very high fire hazard severity zones within the Palisades and Eaton fire boundaries, citing evacuation-route concerns. The City of Los Angeles, Los Angeles County, Pasadena, and Malibu then adopted policies to stop processing SB 9 applications in those areas.

In July 2026, Malibu and Pasadena settled a YIMBY Law lawsuit by agreeing to repeal their local bans and accept pending and future SB 9 applications, while the case continues against Los Angeles County, the City of Los Angeles, Governor Newsom, and Mayor Bass.

Does SB 9 apply in Altadena?

Not for now. Governor Newsom signed SB 1090 on September 30, 2026, temporarily pausing SB 9 in Altadena during Eaton Fire recovery.

The Governor signed SB 1090, the Keep Altadena Land in Altadena Hands Act, on September 30, 2026. As written in the Legislature, the bill exempts Altadena from SB 9 and SB 1123 through 2030; before it passed, 52 of the 5,645 damaged or destroyed Altadena parcels had active permits invoking SB 9.

Is SB 9 worth it compared to building an ADU?

For most homeowners, an ADU is simpler and cheaper, and application numbers reflect that. SB 9 earns its extra complexity mainly when you want a second parcel you can sell, finance, or pass on separately.

Expectations started high. UC Berkeley’s Terner Center estimated in 2021 that SB 9 could make roughly 700,000 new homes financially feasible. Its first-year follow-up found Los Angeles had received 211 SB 9 unit applications and approved 38.

The gap with ADUs is wide. San Francisco received just 32 SB 9 construction applications, compared with more than 460 ADU applications in 2022 and 2023 alone. A Terner researcher called SB 450 a step in the right direction but said more reform is needed before SB 9 projects take off.

Choose based on what you want at the end:

• Rental income, one parcel, simplest permit: an ADU, or an SB 9 two-unit project if you want two full-size primary homes.
• A lot you can sell or borrow against separately: an SB 9 lot split, if you can meet the three-year residency commitment.
• Maximum unit count: an SB 9 two-unit project plus ADUs on an unsplit lot can reach the same four-unit total as a split, without the subdivision step.

Recommended Read: ADU vs. SB 9 for Orange County homeowners → ADU guide

How much does an SB 9 project cost, and how do you finance it?

The lot split paperwork is usually the smallest expense. Utility connections, access easements, and construction are where budgets break, and financing is harder because the new parcel typically starts out tied to your existing mortgage.

Costs vary by city and site, so be wary of any single statewide number. What the law does control is what a city can charge or require. Cities may require utility and access easements, but not right-of-way dedications or offsite improvements, and the state has told cities they cannot charge park in-lieu (Quimby) fees as a condition of an SB 9 lot split.

The budget items that most often surprise owners are separate utility laterals for a rear lot, a recorded access easement, a parcel map from a licensed surveyor, and construction on a lot with limited equipment access. Get a site-specific estimate for each before committing to a split.

Can I split my lot if I still have a mortgage?

Yes, but your lender has a say. When a lot is split, the new parcel generally remains covered by your existing mortgage, so you’ll need the lender’s cooperation to sell, refinance, or borrow against either lot on its own.

Attorneys flagged this when SB 9 passed: a newly created second lot would presumably remain encumbered by the existing mortgage. In practice, that means asking your servicer early how it handles a partial release of the new parcel, and what loan-to-value it will require on the remaining lot.

Construction financing is the second hurdle. A construction loan on a newly created, vacant parcel is underwritten differently from a purchase loan, and many owners discover the gap only after the split records.

What happens to my property taxes after an SB 9 split?

A split by itself generally does not trigger reassessment, because Prop 13 reassesses only on a change in ownership or completed new construction. New homes get their own assessed value when finished, and any lot you sell is reassessed at the sale.

The State Board of Equalization explains that a property’s base year value is reset upon a change in ownership or completion of new construction, and for an addition only the new construction is assessed. Your original home keeps its Prop 13 base, and new units are added at their completed value. Confirm the treatment of your specific split with the Orange County Assessor before you file.

If construction cost is what’s holding you back

A lot can qualify for SB 9 and still sit untouched because the build costs more than an owner has on hand. My company handles construction and renovation with zero upfront cost to you, and we’re repaid from the proceeds when the property sells at close of escrow. That lets you weigh building first against selling as-is or listing, with real numbers for your property. Fill out the short form at [landing page link] and I’ll reach out personally to walk through your options. No pressure, no obligation.

Recommended Read: renovate before you sell with zero upfront cost → renovation program page

I’m thinking of selling. Does SB 9 potential raise my home’s value?

SB 9 potential helps a sale only when the buyer can actually use it. Because a lot split requires the buyer to live on the property for three years, many investor buyers cannot split your lot at all, which narrows who will pay for that potential.

The residency affidavit attaches to whoever applies for the split. Under state guidance, the applicant must intend to live in one of the units as a principal residence for three years, and cities such as Costa Mesa exclude LLCs and other entities from applying. The buyer most likely to value split potential is an owner-occupant, not a fund.

The two-unit path has a broader buyer pool, since it carries no owner-occupancy requirement under SB 9. But if your home has been rented in the last three years, demolition or alteration is off the table under SB 9 until that window passes.

If you want buyers to credit SB 9 potential, document it rather than describe it:

1. Confirm single-family zoning and that no exclusion applies, including fire, flood, or historic status.
2. Check your HOA’s CC&Rs, since SB 9 does not override them.
3. Measure the lot against the 1,200-square-foot and 60/40 rules, and show how a rear parcel would reach the street.
4. Note whether your city is a general-law or charter city, and include its current SB 9 handout.

Recommended Read: cash offer vs. listing your Orange County home → options comparison

Recommended Read: selling an inherited or probate home in Orange County → probate guide

How do I apply for an SB 9 project in Orange County?

In most Orange County cities, a two-unit project is filed as a building permit and a lot split as a parcel map application. Once the city deems your application complete, it has 60 days to approve or deny it.

Each city in Orange County, California, including Anaheim, Santa Ana, Irvine, Huntington Beach, Fullerton, and Costa Mesa, runs its own SB 9 intake. Unincorporated areas follow County of Orange guidance on two-unit developments and urban lot splits. The general sequence looks like this:

1. Confirm eligibility with the city planning counter: zoning, exclusions, and whether the city is a charter city.
2. Check your HOA’s CC&Rs and your mortgage terms before paying for design work.
3. Commission a survey and site plan showing lot lines, access, and utility routes.
4. Submit the application. In Costa Mesa, for example, a two-unit project goes in as a building permit, while a lot split starts as a parcel map and then moves to building permits.
5. Watch the clocks. The city has 30 days to decide whether the application is complete, then 60 days from receipt of a complete application to approve or deny it.
6. Sign and record the owner-occupancy affidavit if you are splitting the lot.

If the city denies the application, SB 450 requires a written explanation of each deficiency and how to cure it, which gives you a path to resubmit.