SB 9 promised to crack open single-family zoning across California, letting many R-1 lots split and add units. The reality in 2026 is messier: the core law stands, but a court fight over charter cities is still unresolved. Here is what SB 9 does, and where the uncertainty lies.
What SB 9 Actually Allows
SB 9 (the California HOME Act) requires cities to ministerially — meaning without a discretionary hearing or CEQA review — approve two things on eligible single-family lots: (1) up to two primary units on a lot (effectively allowing a duplex where only a single-family home was allowed), and (2) an urban lot split dividing one lot into two. Combine both and a single original R-1 lot can, in some cases, end up with as many as four units.
It applies to parcels zoned for single-family residential in urbanized areas, with eligibility conditions and exclusions (see below). It does not rezone the whole state — it overrides certain local rules for qualifying single-family lots.
Eligibility, Exclusions, and the Owner Affidavit
SB 9 has guardrails. It generally does not apply to parcels in historic districts, certain hazard zones (high fire, flood, earthquake fault, wetlands, conservation land), or where it would require demolishing affordable or rent-restricted housing or housing occupied by a tenant in recent years. There are limits on demolishing existing exterior walls in some cases.
For an urban lot split, the law requires the applicant to sign an affidavit agreeing to occupy one of the units as their primary residence for at least three years (this owner-occupancy requirement applies to lot splits; it is not imposed the same way on the two-unit path). Resulting lots must each be at least 40% of the original and meet a minimum size. Short-term rentals of the new units are typically prohibited.
How SB 450 Changed SB 9 (Effective 2025)
SB 450, effective January 1, 2025, strengthened SB 9. It declared that addressing the housing shortage is a matter of statewide concern that applies to all cities, including charter cities; required local agencies to approve or deny a complete SB 9 application within 60 days; required denials to specify the deficiencies and how to cure them; and limited cities' ability to pile on extra objective standards beyond what SB 9 allows.
In short, SB 450 was the Legislature's response to cities slow-walking SB 9 and to the charter-city lawsuit — an attempt to close the loophole and speed approvals.
The Charter-City Court Fight (Why It's Still Uncertain)
This is the part buyers and investors must understand. In April 2024, a Los Angeles County Superior Court ruled in a suit by five charter cities (Carson, Redondo Beach, Torrance, Whittier, and Del Mar) that SB 9 was unconstitutional as applied to charter cities, reasoning that the law intruded on charter cities' constitutional 'home rule' over municipal affairs and did not clearly serve a statewide concern because it does not mandate affordable housing.
After SB 450 expressly declared SB 9 a statewide concern binding charter cities, the matter went up on appeal. On November 12, 2025, the Second District Court of Appeal sent the case back to the trial court to reconsider in light of SB 450's new language. As of mid-2026, the question of whether SB 9 fully applies in charter cities is not finally resolved. (California has roughly 120+ charter cities; most cities are general-law cities where SB 9 applies.) If your target property is in a charter city, confirm the current local status before you count on SB 9.
What This Means If You're Buying or Investing
For a general-law city, SB 9 is a real tool: a path to a duplex or a lot split with ministerial approval. For a charter city, treat SB 9 as uncertain pending the courts and verify the city's current policy. Either way, SB 9 does not guarantee a profitable project — lot size, minimum-lot rules, the 40% split rule, utility and access costs, the 3-year owner-occupancy affidavit, and financing all affect feasibility. Run the numbers and confirm eligibility with the planning department for the exact parcel before relying on it.
The Fine Print — This Is Not Legal Advice
Brian Cooper is a licensed REALTOR® with eXp Realty, not an attorney, land-use planner, or licensed surveyor. This guide is general educational information, not legal, tax, or land-use advice, and zoning law changes often. Zoning designations, overlays, and development standards are set and interpreted by each city or county, and state housing laws are actively litigated and amended. Before you buy, build, split, or invest, verify the zoning, overlays, and development feasibility for a specific parcel with the local planning department and confirm current state law — ideally with a land-use attorney or licensed professional.
Frequently Asked Questions
What does SB 9 let me do?
On an eligible single-family (R-1) lot, SB 9 allows ministerial approval of up to two primary units and an urban lot split into two parcels, so an original lot can sometimes end up with up to four units. It applies to qualifying parcels in urbanized areas, with exclusions for certain historic, hazard, and tenant-occupied properties.
Does SB 9 require me to live on the property?
For an urban lot split, yes — the applicant must sign an affidavit agreeing to occupy one unit as a primary residence for at least three years. The two-unit path does not impose owner-occupancy the same way. Confirm current requirements with your city.
Is SB 9 still in effect in 2026?
Yes, SB 9 remains in effect, and SB 450 strengthened it as of 2025. However, its application to charter cities is unsettled: a 2024 trial court struck it down as applied to charter cities, and in November 2025 an appeals court sent the case back for reconsideration in light of SB 450. The charter-city question is not finally resolved.
What is a charter city, and why does it matter for SB 9?
A charter city has adopted its own charter giving it 'home rule' over municipal affairs under the California Constitution. The lawsuit argued SB 9 intrudes on that authority. Most California cities are general-law cities where SB 9 applies; the dispute is specifically about charter cities. Verify which type your target city is.
Did SB 450 fix the charter-city problem?
SB 450 (effective 2025) declared SB 9 a statewide concern binding charter cities and tightened approval rules. Whether that fully resolves the constitutional challenge is what the courts are still deciding as of 2026, so it is not safe to assume the issue is settled.
Can I use SB 9 for short-term rentals?
Generally no. SB 9 units typically cannot be used as short-term rentals (rentals shorter than 30 days), and an urban lot split carries the owner-occupancy affidavit. Confirm the specific local rules before planning any rental use.
