Zoning law explained
California SB 9 Explained: Lot Splits, Duplexes, and What You Can Build
What California Senate Bill 9 allows on single-family lots, which parcels qualify, the owner-occupancy and rental limits, the 2024 amendments in SB 450, and the status of the charter city lawsuit as of October 2026.
California Senate Bill 9 is a state law, in effect since January 1, 2022, that requires cities and counties to approve two homes on a lot in a single-family zone, and to approve splitting such a lot in two, without a public hearing or discretionary review. Used together, the two provisions allow up to four homes where one was allowed before. It applies only to qualifying parcels in urban areas, and it comes with owner-occupancy, rental, and site restrictions.
What SB 9 is and how it works
SB 9 (Chapter 162, Statutes of 2021) was signed on September 16, 2021 and added two sections to the Government Code.
Two-unit development (Gov. Code 65852.21). A proposed housing development of no more than two residential units in a single-family residential zone must be considered ministerially, without discretionary review or a hearing.
Urban lot split (Gov. Code 66411.7). A local agency must ministerially approve a parcel map that divides a single-family lot into two, if both new parcels are at least 1,200 square feet and neither is smaller than 40 percent of the original lot. The agency is not required to allow more than two units on each resulting parcel.
Cities can apply objective zoning, subdivision, and design standards, within limits:
- Standards cannot physically prevent two units of at least 800 square feet each.
- Side and rear setbacks cannot exceed four feet, and no setback can be required for an existing structure.
- Parking is capped at one space per unit, and none can be required within half a mile walking distance of a high-quality transit corridor or major transit stop.
- For a lot split, the agency cannot require dedications of right-of-way or construction of off-site improvements.
Who and where it applies
A parcel qualifies only if all of these are true:
- It is in a single-family residential zone.
- It is in a city whose boundaries include part of a census-designated urbanized area or urban cluster, or, in an unincorporated area, it lies wholly within one.
- It is not a listed historic landmark, and the project does not involve a contributing structure in a historic district.
- It is outside the categories listed in Gov. Code 65913.4, subdivision (a)(6)(B) through (K), which include prime farmland, wetlands, very high fire hazard severity zones, hazardous waste sites, earthquake fault zones, flood hazard areas, and conservation lands. Several have exceptions.
- The project would not demolish or alter rent-restricted or rent-controlled housing, or housing a tenant has occupied in the last three years, and the Ellis Act has not been used to withdraw units there in the last 15 years.
Key dates
- January 1, 2022: SB 9 took effect.
- June 18, 2024: Los Angeles County Superior Court entered judgment against SB 9 in a charter city case.
- January 1, 2025: SB 450 amendments took effect.
- November 12, 2025: Court of Appeal reversed that judgment and returned the case to the trial court.
- June 30, 2026: SB 1426 made nonsubstantive amendments to both sections.
Current status
Do this in Plotzy
Ask the zoning code a question and get a cited answer
Zoning AI reads the ordinance for you. Ask about permitted uses, setbacks, FAR, height, or parking for a specific parcel and get the answer with the section it came from.
- Two-level zoning on every parcel, nationwide
- Plain-English answers with section-level citations
- Filter parcels by zoning before you spend a day on due diligence
7-day free trial
SB 450. Signed September 19, 2024, it tightened the process. A local agency must approve or deny a complete SB 9 application within 60 days, or it is deemed approved. Cities cannot apply standards to SB 9 projects that do not apply uniformly to development in the underlying zone.
Litigation. Five charter cities (Redondo Beach, Carson, Torrance, Whittier, and Del Mar) challenged SB 9, and in June 2024 the trial court entered a judgment holding it unconstitutional and barring its enforcement against them. The Attorney General appealed. On November 12, 2025, in an unpublished opinion, the Court of Appeal reversed the judgment because SB 450 had changed the statutory language the trial court relied on, and sent the case back for reconsideration. It expressed no opinion on the merits. This page does not reflect any trial court ruling after that remand, so check the case status if your parcel is in a charter city.
What this lets you build
Without a lot split: two homes on one single-family lot, as a duplex or two detached units.
With a lot split: two lots, each with up to two homes, for up to four homes on what was one parcel.
Approvals removed: no rezoning, conditional use permit, public hearing, or discretionary design review.
Limits that remain:
- Owner occupancy for lot splits. The applicant must sign an affidavit of intent to live in one of the units as a principal residence for at least three years after the split. Community land trusts and qualified nonprofits are exempt.
- One split only. A parcel created by an SB 9 split cannot be split again under SB 9, and the same owner, or anyone acting in concert, cannot use SB 9 to split adjacent parcels.
- Residential use only, and rentals must be for terms longer than 30 days.
- Private covenants. SB 9 limits what local agencies can require. Its two sections say nothing about homeowners association covenants, so check title.
How to check a specific parcel
- Confirm the zoning district is single-family residential and the parcel is in an urbanized area or urban cluster.
- Check lot area. A split needs at least 2,400 square feet unless the city has adopted a smaller minimum.
- Screen for exclusions: historic status, fire hazard severity zone, flood zone, and fault zone.
- Check tenancy and Ellis Act history.
- Read the city's SB 9 ordinance, and pull title for covenants.
In Plotzy, filter parcels by zoning designation and lot size to find single-family lots large enough to split, then ask Zoning AI "What are the setback and height standards for this lot?" for an answer with the code section cited.
Frequently asked questions
What does SB 9 allow?
Two homes on a single-family lot, and a one-time split of that lot into two parcels with up to two homes each.
Do I have to live on the property to use SB 9?
For a lot split, yes. The applicant signs an affidavit of intent to occupy one of the units as a principal residence for at least three years. The two-unit section contains no owner-occupancy requirement.
Does SB 9 apply in charter cities?
That question is in litigation. A 2024 trial court judgment against SB 9 in a case brought by five charter cities was reversed and sent back for reconsideration in November 2025. Confirm the current status with the city.
Can a city deny an SB 9 application?
Only on narrow grounds: the project fails objective standards or eligibility rules, or the building official makes a written finding of a specific adverse impact on public health and safety.
Sources
The bills, statutes, court decisions, and agency documents cited on this page were checked on October 4, 2026. These laws have been amended and litigated since they passed, so confirm the current text and status before relying on any detail. This page is general information, not legal advice.
- California Legislative Information: SB 9 (2021), chaptered text. Chapter number, signing date, the two sections added.
- California Legislative Information: Government Code Section 65852.21. Two-unit rule, 800 square foot and setback limits, parking, 60-day deadline, tenant and historic exclusions, rental term, 2026 amendment note.
- California Legislative Information: Government Code Section 66411.7. Lot split sizes, location and zone tests, owner-occupancy affidavit, one-split rule, two-unit cap per parcel, dedications.
- California Legislative Information: Government Code Section 65913.4. Excluded site categories in subdivision (a)(6)(B) through (K).
- California Legislative Information: SB 450 (2024). Chapter 286, signing date, 60-day deadline, uniform standards.
- California Legislative Information: SB 1426 (2026). Chapter 56, approved June 30, 2026, nonsubstantive changes.
- California Legislative Information: California Constitution, Article IV, Section 8. Regular session statutes take effect the following January 1, which gives the January 1, 2022 and January 1, 2025 dates.
- California Court of Appeal, Second District: City of Redondo Beach v. Bonta, B338990 (November 12, 2025, unpublished). The five cities, the June 18, 2024 judgment, the reversal and remand.
- California Attorney General: notice of appeal press release (June 21, 2024). The state's appeal of the trial court judgment.
Related reading
- What Is Zoning Reform? A Plain Guide for Land Buyers and Developers
What zoning reform means, the main types (upzoning, missing middle housing, parking, ADUs, lot sizes, by-right approval), who is passing it, and what it changes for a specific site.
- What Is Missing Middle Housing? Zoning Rules and What You Can Build
What missing middle housing means, which state and city laws now allow duplexes, triplexes, fourplexes, and townhouses on single-family lots, and what those laws let you build on a residential parcel.
- Minimum Lot Size Reform Explained: What Smaller Lot Rules Change for a Subdivision
What minimum lot size rules are, how Texas SB 15, Austin, Houston, and California have lowered them, and what smaller lot minimums change for subdivision yield, approvals, and the limits that remain.
- What Is an Accessory Dwelling Unit (ADU)? Zoning Rules and What You Can Build
What an ADU is, how state and city ADU laws work in California, Washington, Colorado, Massachusetts, and New York City, and what they let you add to a residential lot without a rezoning.
- What Is R-1 Zoning? Single-Family Residential Districts Explained
What R-1 zoning usually allows, the lot size, height, and setback rules that come with it, how Phoenix, Detroit, Los Angeles, and New York define it, and the recent reforms that let R-1 lots hold more than one home.
- How to Find Out What a Property Is Zoned For (Any US Address)
A step-by-step method for looking up a parcel's zoning, reading the designation, telling permitted from conditional uses, catching overlays and planned developments, and confirming it with the planning department.