What Are SB 9 and SB 1123, and Can You Split Your Lot in Los Angeles County?

What Does SB 9 Actually Let You Do With Your Lot?

SB 9, also known as the California HOME Act, gives owners of most single-family zoned lots two ministerial options: build a duplex (up to two units) on your existing lot, or split the lot into two separate parcels and build up to two units on each — up to four total homes on what used to be one single-family lot. The lots created by an urban lot split have to be roughly equal, within a 60/40 split, and each new parcel must be at least 1,200 square feet, with the original lot at least 2,400 square feet to qualify. Local agencies can apply objective development standards like setbacks, similar to ADU rules, but they can't impose subjective design requirements just to make a project harder to approve.

Who Qualifies for an SB 9 Lot Split?

The lot has to be zoned single-family residential and sit outside high-risk areas — coastal zones, wetlands, and land with significant wildfire, flood, or earthquake hazard exposure are excluded. One of the biggest catches: the owner has to sign a recorded affidavit promising to occupy one of the units on one of the new parcels as their primary residence for at least three years, which is meant to discourage pure speculation. You also can't use SB 9 to demolish a unit that's been rented out within the past three years, and short-term rentals under 30 days aren't allowed in the new units.

What's Different About SB 1123?

SB 1123, which expanded the 2023 Starter Home Revitalization Act (SB 684), took effect July 1, 2025, and opened ministerial small-lot subdivision to vacant single-family-zoned lots up to 1.5 acres, as long as the site is surrounded by substantially urban development. Unlike SB 9's two-lot cap, SB 1123 allows up to ten units through the ministerial process, with each resulting parcel required to be at least 1,200 square feet. ADUs and junior ADUs don't count against that ten-unit limit if the local agency allows them. There's no owner-occupancy requirement here — SB 1123 is built for builders and developers assembling small-lot "starter home" subdivisions, not for a homeowner looking to split their own backyard.

How Fast Does the Approval Process Move?

Both laws require ministerial review, which means the city or county can't hold public hearings or exercise discretion to deny a qualifying project — they can only check it against objective standards. Under SB 1123, the local agency has 60 days to approve or deny a qualifying application, and if it misses that window, the project is deemed approved. SB 9 doesn't set an identical statutory clock in the same way, but because review is ministerial, most Los Angeles County and city planning departments process complete SB 9 applications in a matter of weeks rather than the months a discretionary subdivision would take.

Does This Apply the Same Way in Every LA County City?

Not exactly. SB 9 and SB 1123 are state laws that override conflicting local zoning, but individual cities and the county's unincorporated areas can still adopt their own objective development standards — setbacks, height limits, lot coverage — as long as those standards don't functionally block projects that would otherwise qualify. Some cities have been slower than others to update their local ordinances to reflect these laws, so it's worth checking with the specific city's planning department (or LA County Planning for unincorporated areas) before assuming your lot automatically qualifies.

Frequently Asked Questions

Can I use SB 9 and SB 1123 on the same lot?

No — they're separate pathways with different eligibility rules. SB 9 works on an existing single-family lot regardless of whether it has a home on it already; SB 1123 only applies to vacant single-family lots up to 1.5 acres.

Do I have to live in one of the new units under SB 9?

Yes, if you're doing an urban lot split. You have to sign a recorded affidavit committing to occupy one of the units on one of the new parcels as your primary residence for at least three years.

Is there a minimum lot size to qualify for SB 9?

Your existing lot generally needs to be at least 2,400 square feet, since each resulting parcel after the split must be at least 1,200 square feet.

Does SB 1123 require me to live in one of the new homes?

No. SB 1123 has no owner-occupancy requirement — it's designed for building and selling small-lot starter homes, not for a homeowner splitting their own property.

Updated for September 2026.