Insights

SB 684 vs. SB 1123: What Changed for California Small-Lot Homes

Oliver Thornton · October 24, 2026

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.

SB 684 created California’s Starter Home Revitalization Act, a ministerial path for subdividing a qualifying lot into as many as ten fee-simple homes. SB 1123, effective July 1, 2025, amended it. If you have read about one and not the other, this summary explains what the second law changed and what it left alone.

The One-Sentence Summary

SB 684 applied the streamlined process to multifamily-zoned land; SB 1123 extended it to vacant lots in single-family zones, refined several standards, and added tenancy in common as a permitted ownership form.

What Changed

Topic	SB 684 (original)	After SB 1123
Eligible zoning	Multifamily zones	Adds vacant lots in single-family zones
Site size	Up to 5 acres	Up to 5 acres (multifamily); 1.5 acres (vacant single-family)
Minimum new lot size	600 sq ft	600 sq ft (multifamily); 1,200 sq ft (vacant single-family)
Home size	Average of 1,750 sq ft	Clarified as 1,750 net habitable sq ft, with a definition
Frontage	Local minimums limited	Minimum frontage requirements removed
Ownership forms	Fee simple, CID, co-op, community land trust	Adds tenancy in common

What Stayed the Same

Ministerial approval. No discretionary hearing and no CEQA review for a qualifying project.
The 60-day clock for a decision on a complete application.
The 10-lot, 10-home cap, excluding a remainder parcel.
Setback and floor-area floors that make compact site plans possible: side and rear setbacks capped at four feet, and floor-area ratio floors of 1.0 or 1.25 depending on the number of homes.
Site screens for fire hazard, flood, fault, habitat and contamination, the urban-perimeter test, and the bar on sites already split under SB 9 or the Act.

Why SB 1123 Matters, and Its Limits

SB 1123 opened single-family neighborhoods to small-lot subdivision for the first time, which is a significant expansion of where starter homes can be built. Its main limit is the vacancy requirement: a single-family lot generally has to be empty, or hold only an abandoned and uninhabitable structure, to qualify. A single-family lot with an occupied house on it usually does not. That is why most of the active SB 684 projects on the Westside, including ours, sit on multifamily-zoned lots. For the details, see our SB 1123 requirements guide.

A Note on Later Amendments

The framework is still moving. AB 130 also amended the Act effective July 1, 2025, and local agencies continue to publish their own implementation procedures. Treat any summary, including this one, as a starting point, and confirm the current rules with the city before relying on them.

Frequently Asked Questions

Is SB 1123 a separate law from SB 684?
SB 1123 amended the Starter Home Revitalization Act that SB 684 created. The two work as one framework: SB 684 covers multifamily-zoned land and SB 1123 extends the same process to vacant single-family lots.

When did SB 1123 take effect?
July 1, 2025.

Did SB 1123 change the 10-unit limit?
No. Projects under both remain capped at 10 lots and 10 homes, with an average home size of no more than 1,750 net habitable square feet.

Which is better for a developer, SB 684 or SB 1123?
It depends on zoning and site condition. SB 684 sites are multifamily-zoned and can have an existing house; SB 1123 sites must be vacant single-family lots. Many small-lot developers prefer SB 684 sites because qualifying is more straightforward.

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.

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