SB 1123 • The Early Window
SB 1123 Is Where ADUs Were In 2016
A by-right path to subdivide qualifying vacant residential land into up to 10 ownership-oriented homes.
Ministerial approval for qualifying projects — no CEQA, no discretionary hearings.
In effect since July 1, 2025. And the market hasn’t caught up yet.
- Bill
- SB 1123 — an expansion of the Starter Home Revitalization Act (SB 684)
- Effective
- July 1, 2025
- Impact
- Ministerial subdivision of qualifying lots into up to 10 parcels or dwelling units
- Builds on
- SB 684 (2023), and the broader ADU / SB 9 “missing middle” lineage
SB 1123 takes the by-right subdivision path SB 684 opened and extends it to qualifying vacant single-family lots. For sites that qualify, you can carve a single parcel into starter homes or ownership interests without a discretionary fight.
Eligibility is real, and it matters. In broad strokes, qualifying sites must be:
- Zoned to allow multifamily residential dwelling use; or
- Vacant and zoned for single-family residential development.
The law also layers in objective design standards, environmental screening, and tenant and affordability protections, and it allows more than one ownership structure — fee-simple lots in some cases, common-interest or cooperative forms in others.
Application of Local Objective Standards
The SHRA generally allows cities to impose objective zoning, subdivision, or design standards, as long as they are not explicitly prohibited by the law and would not have the effect of imposing a prohibited standard. The following objective standards cannot be applied to SHRA projects:
- Density
- Can’t block up to 10 small parcels of 600–1,200 sf.
- Floor Area Ratio
- Guaranteed at least 1.0 (3–7 units) or 1.25 (8–10 units).
- Setbacks
- No rear or side setback beyond 4 ft from the lot line.
- Building Separation
- No unit-to-unit or building-separation requirement.
- Lot Dimensions
- No minimum lot width, depth, or frontage.
- Parking
- Max 1 space per unit — none near transit or car-share.
So the headline is simple; eligibility is not. Whether a given parcel qualifies — and as how many units, under which ownership model — has to be checked against the statute and LA’s objective standards site by site. That’s the work.
One qualifying parcel in. Up to ten homes or ownership interests out.
A Housing Law Today. A Whole Industry In Ten Years.
Here’s what we’ve watched happen before.
When California opened up ADUs around 2016–17, land-use professionals started folding them into designs almost immediately — an easy way to add square footage beyond the envelope. The broader market took another eight to ten years to fully adopt. Now there are ADU design-build firms, ADU lenders, ADU Instagram pages. It’s common knowledge. It built an entire industry.
Then the same language carried forward. SB 9 brought urban lot splits and two-unit development. SB 684 opened by-right for-sale subdivision. And now SB 1123 extends that lineage to vacant single-family lots, scaling the same core idea toward as many as ten homes.
If SB 1123 follows the ADU adoption curve, we’re at the very front of it. That puts roughly three to five years before the market starts adopting in earnest, and close to a decade before it’s common knowledge. Today, relatively few developers, investors, and land-use professionals are actively underwriting opportunities through SB 1123.
This is a forecast, not a guarantee. But the people who learned ADUs in 2016 weren’t guessing either. They were just early.
- 2016–17 • ADUs
- State reform opens up accessory units. ~10 years to full market adoption.
- 2021 • SB 9
- Urban lot splits and two-unit development on single-family lots.
- 2023 • SB 684
- Starter Home Revitalization Act — by-right for-sale subdivision.
- 2025 • SB 1123
- You are here. Extends the path to vacant single-family lots, up to 10 units.
- ~2028–2035 • Projected
- Broad market adoption, if the ADU pattern holds. Whitestone estimate.
This Isn’t Theoretical
The City of LA, cityLAB-UCLA and LA4LA just ran Small Lots, Big Impacts — a competition to reimagine small, overlooked LA parcels as starter homes. It drew 350+ submissions from 36 countries and named its winning designs. Phase two pairs winning teams with city-owned land to actually build them.
It’s the clearest preview anywhere of what SB 1123-era small-lot housing looks like — and a directory of the architects who want to build it.
That’s where we come in. We put developers and investors in the same room as these architects, then handle the part that actually unlocks the parcel: subdivisions, parcel and tract maps, and the entitlements that get it approved.
We Do This Work
Subdivision and entitlement is the skill SB 1123 rewards. Two from our portfolio:
Lyceum Two Unit SB9
Westside, 90066 • Michael Matthews Studio, AIA
A single-family lot, split under SB 9 into a two-unit development with an ADU over the main house — fee-simple density on a parcel that started as one home. SB 9 tops out at a lot split plus two units; SB 1123 carries the same subdivision logic to a bigger envelope. Different statute, more units — same core skill: getting it entitled.
SB9 Two Unit Development, Venice
Venice Coastal, 90029 • Guban Architecture
The first approved SB 9 two-unit development in the Venice Specific Plan — a coastal overlay where almost nothing moves by-right. A 2nd primary unit added to a single-family lot, cleared through a Coastal Development Permit and meticulous site-context work by Steven Guban, AIA. A genuine first, on some of the hardest ground in the city to entitle.
If you’re sitting on vacant residential land — or weighing a buy — SB 1123 may have just changed what that parcel can become.
The question worth asking before you acquire: has the site been run as one home, or as up to ten? Because right now, almost no one is asking it yet. That’s the window.
Talk soon, Jake & Team Whitestone