General information only. This article is educational and is not legal, tax, financial, lending or investment advice. Do your own due diligence and confirm everything with your own qualified professionals before relying on it. Read the full disclaimer.
From January 1, 2027, California has two ministerial paths to new fee-simple, for-sale homes on infill land. SB 684 and SB 1123, the Starter Home Revitalization Act, cover projects of up to ten homes. AB 1751, the Missing Middle Townhome Ownership Act, covers townhome projects of up to 150 homes.
Both skip public hearings and CEQA review, both run on a 60-day approval clock, and both let each home sit on its own lot. They are built for different sites. This article explains how to tell which one a Los Angeles site belongs under.
The Short Answer
- A single lot with room for four to ten homes on low-density multifamily zoning is usually an SB 684 site.
- A larger or more densely zoned multifamily site that can hold more than ten homes is usually an AB 1751 site.
- A vacant single-family lot can use SB 1123 (up to 1.5 acres) or AB 1751 (if it has no permanent home, or only an abandoned, uninhabitable one).
The details below decide the close cases.
Side by Side
| SB 684 / SB 1123 | AB 1751 | |
|---|---|---|
| Maximum homes | 10 | 150 |
| Housing type | Any | Townhomes, three stories or fewer |
| Average home size | Up to 1,750 net habitable sq ft | Up to 1,750 net habitable sq ft |
| Site test from 2027 | Base zoning allows no more than 15 units (or 26,250 sq ft of residential floor area) | At least 75% of the state default density; local minimum density no higher than 50 units per acre |
| Site size | No cap on multifamily sites from 2027; 1.5 acres on vacant single-family lots | No maximum |
| Minimum new lot | 600 sq ft multifamily, 1,200 sq ft single-family (smaller with averaging from 2027) | 600 sq ft |
| Affordability | On certain Housing Element sites | 10% lower-income homes on projects of 11 or more |
| Approval | Ministerial, no CEQA, 60 days | Ministerial, no CEQA, 60 days |
Five Questions That Decide It
1. How many homes can the site hold?
This is the first cut. SB 684 stops at ten homes. If a site can reasonably hold more than ten, AB 1751 is the only one of the two that can approve all of them on one map.
2. How dense is the base zoning?
From 2027, SB 1116 limits SB 684 to sites whose base zoning allows no more than 15 units, or 26,250 square feet of residential floor area where the zoning sets no unit maximum. Density bonuses, ADUs and overlays don’t count. A low-density multifamily lot clears that easily; a large or densely zoned parcel may not.
AB 1751 runs the other way. It requires a project to reach at least 75 percent of the state default density, which in Los Angeles County is generally about 22.5 homes per acre. It also excludes sites whose local minimum density is above 50 units per acre.
3. Do you want townhomes or something else?
AB 1751 is townhomes only: homes of three stories or fewer that share a wall with a neighbor, or sit no farther apart than the Building Code’s minimum fire separation distance. SB 684 allows any housing type, including detached small-lot homes.
4. Will the affordability requirement work?
AB 1751 projects of 11 or more homes must sell at least 10 percent of the homes to lower-income households at an affordable housing cost, for at least 45 years. See how the AB 1751 affordability requirement works. SB 684 projects carry an affordability requirement only on certain Housing Element sites.
5. Does the site clear each law’s exclusions?
The two lists overlap but are not identical. Both exclude high and very high fire hazard severity zones, wetlands, protected habitat and conservation land, and both protect rent-controlled housing and sites with Ellis Act withdrawals in the past 15 years. AB 1751 also excludes:
- Parcels that held five or more homes at any time in the past five years.
- Historic resources and parcels in historic districts.
- Housing Element sites designated for lower-income units.
- Sites subject to SB 79, the 2025 transit-oriented upzoning law.
SB 684 has its own anti-displacement screen, including sites with tenants in the past five years. A site that fails one law’s screen may still pass the other’s.
Three Example Sites
| Site | Likely path | Why |
|---|---|---|
| 6,000 sq ft multifamily lot in Culver City with one older house | SB 684 | Fits about six homes, well under ten; low-density zoning clears the 2027 SB 684 test |
| Half-acre multifamily-zoned parcel with one older owner-occupied house | AB 1751 | Holds more than ten townhomes at the density floor, so it is too large for SB 684; at 11 or more homes, 10% must be affordable |
| Vacant 9,000 sq ft single-family lot | SB 1123, or AB 1751 if it can meet the density floor | Both laws reach vacant single-family land; the number of homes and product type decide it |
These examples are illustrative. Each depends on the site’s exact zoning, history and the city’s implementation rules.
How We Use the Two Laws
Assemble Capital builds fee-simple homes on Los Angeles infill land and sells them one at a time to owner-occupants. SB 684 is our core small-lot strategy. As AB 1751 takes effect, part of our syndication model will be facilitating AB 1751 townhome projects where a site qualifies. We screen each site under both laws before we buy it, because the choice of path shapes the site plan, the timeline and the exit.
Owners and agents with a site that may fit either law can submit it here.
Frequently Asked Questions
What is the difference between AB 1751 and SB 684?
SB 684 and SB 1123 allow up to ten homes of any type on a qualifying lot. AB 1751 allows up to 150 townhomes of three stories or fewer, requires at least 75% of the state default density, and requires 10% affordable homes on projects of 11 or more. Both are ministerial and exempt from CEQA.
Can a site use both SB 684 and AB 1751?
A project uses one path or the other. The choice depends mainly on how many homes the site can hold, its zoning, and which law’s exclusions it clears.
Which law applies to a large multifamily-zoned lot?
From January 1, 2027, SB 684 is limited to sites whose base zoning allows no more than 15 units, or 26,250 square feet of residential floor area where zoning sets no unit maximum. Denser multifamily sites will generally look to AB 1751 instead, provided their minimum density is no more than 50 units per acre.
Does AB 1751 allow detached homes?
Only if they qualify as townhomes: homes that share a wall with a neighbor, or sit no farther apart than the Building Code’s minimum fire separation distance. SB 684 allows any housing type.
Do both laws allow fee-simple lots?
Yes. Both allow each home on its own fee-simple lot with a minimum of 600 square feet on multifamily-zoned land, and neither requires a homeowners association.
Sources and Review
Summarized from the chaptered text of AB 1751 (Chapter 781, Statutes of 2026) and from our articles on SB 684 and SB 1123 and SB 1116. Both 2026 laws apply from January 1, 2027, and cities will publish their own implementation procedures. Confirm current rules with the local agency before relying on them.
Important Disclaimer
This article is published by Assemble Capital for general informational and educational purposes only. It is not legal, tax, accounting, lending, appraisal, real estate brokerage or investment advice, and it is not an offer to sell or a solicitation of an offer to buy any security. Laws, regulations, government programs, lending practices, market conditions and local procedures change often and vary by jurisdiction and by property. The information here may be incomplete, out of date or not applicable to your situation, and we have no obligation to update it.
No one, including investors, lenders, property owners, buyers, sellers, agents, brokers, wholesalers or developers, should rely on this article in making any decision. Before acting on any topic discussed here, independently verify the information and conduct your own due diligence with qualified legal, tax, financial, lending, appraisal and real estate professionals and the applicable government agencies.
References to projects, timelines, approvals, appraisals, financing, prices or market conditions are illustrative, may change, and are not predictions, promises or guarantees of any result. Past performance is not indicative of future results.
Reading this article or contacting us does not create an attorney-client, advisory, fiduciary, agency, brokerage or other relationship with Assemble Capital, its affiliates or its principals. Assemble Capital makes no representation or warranty, express or implied, as to the accuracy, completeness or timeliness of this content and, to the fullest extent permitted by law, disclaims all liability for any loss or damage arising from any reliance on it. Use of this site is subject to our Terms of Service and Risks & Disclosures.
Work With Us
Investing, or Have a Property?
Contacting us is not an offer, commitment or investment. Any offering is made only through definitive offering documents to eligible investors with whom we have a pre-existing relationship.