California SB 9, SB 684 and SB 330: Considerations for Developers

By Matt Miles

Disclaimer: This information is from sources believed to be reliable and is provided as a courtesy. We are not providing legal advice and make no representation as to the accuracy of this information. Hire a good land use attorney and engineer! Always confirm city-specific administrative bulletins and checklists as local standards (e.g., design, frontage, utilities) can affect project feasibility.

California’s housing legislation has opened up new pathways for small-scale development, but each option comes with its own trade-offs that are easy to overlook. Whether you’re looking at adding units under SB 9, pursuing a small-lot subdivision through SB 684, or relying on SB 330 to protect your entitlements, the details matter. From owner-occupancy requirements to exit strategy flexibility and timing advantages, understanding how these acts actually play out on the ground is key before you commit to a deal.

SB 9 (Two-Unit & Urban Lot Split): Enables two units on a single-family–zoned lot, and an optional lot split (max four units across both lots). Procedural if eligible. Lot split path imposes a 3-year owner-occupancy covenant; two-unit (no split) generally has no OO requirement. 30-day minimum rental rule applies.

SB 684 (as refined by SB 1123): Creates a procedural ‘fast lane’ for small-lot subdivisions and qualifying housing developments up to 10 units on infill parcels (typically ≤5 acres in urbanized areas). No owner-occupancy covenant; geared to fee-simple townhouse/rowhome exits.

SB 330 (Housing Crisis Act): A process shield—locks in rules/fees at the preliminary application, caps hearings at five, and prevents downzoning and moratoria. Does not create unit yield by itself; it protects and expedites housing entitlements you pursue under local or state programs.

Core Purpose

SB 9:
By-right 2 units on SFR lots; optional urban lot split for fee-simple outcome (up to 4 total units across both lots).

SB 684:
Procedural small-lot subdivision/housing development on infill parcels; up to ~10 units with streamlined maps.

SB 330:
Process protections for housing: vesting via preliminary application, limit hearings, block downzoning.

Maximum Units

SB 9:
Up to 2 units on one lot (duplex or two detached). With an urban lot split: two lots × 2 units = 4.

SB 684:
Up to 10 fee-simple lots/units (city-specific admin bulletins may confirm the cap).

SB 330:
No direct yield increase; protects the yield you propose under local/state zoning programs.

Ideal Use Case

SB 9:
2x SFR, or 2x duplexes on SFR lots; BRRRR or fee-simple exits.

SB 684:
GUC townhouse (≤10 units) with fee-simple sales and conventional take-out per home.

SB 330:
Any housing project seeking certainty: file prelim early to freeze rules/fees and cap hearings.

Key Eligibility Limits

SB 9:
No recent tenant occupancy (3-year look-back), no historic districts, hazard/utility/service limits; parcel must meet SB 9 map/lot criteria.

SB 684:
Urbanized area/infill, parcel size (commonly ≤5 acres), hazard overlays excluded; city checklists clarify criteria.

SB 330:
Project must qualify as a “housing development”; replacement housing and right-to-return if protected units are affected.

Owner-Occupancy/Hold

SB 9:
Two-unit (no split): generally no OO covenant. Urban lot split: 3-year owner-occupancy hold affidavit recorded.

SB 684:
No owner-occupancy requirement; it’s a process statute.

SB 330:
No owner-occupancy requirement; it’s a process statute.

Rental Rules (STR)

SB 9:
Units may not be rented for <30 days.

SB 684:
No special STR rule in statute; local STR ordinances govern.

SB 330:
No special STR rule; local ordinances govern.

Approval Type

SB 9:
Procedural if eligible (objective standards only).

SB 684:
Procedural if eligible (objective standards only). 60 day approval window for lot split applications

SB 330:
Discretion remains, but capped: ≤5 public hearings post-completion; standards frozen at prelim app.

Typical Zoning

SB 9:
Single-family residential (R-1/RS) parcels that meet SB 9 eligibility.

SB 684:
Urbanized/infill areas; often multifamily/mixed zones or residential where small-lot plats are feasible. Min. 600 sqft parcel.

SB 330:
Any housing/mixed-use (≥2/3 resi) project seeking entitlement—pairs with local/state yield tools.

Common Pitfalls

SB 9:
Triggering tenant protections or historic-area exclusions; assuming lot split without honoring 3-year OO.

SB 684:
Missing “infill/urbanized” criteria or hazard exclusions; assuming 10 units without checking local requirements.

SB 330:
Failing to file prelim app early; not accounting for replacement-unit obligations when touching existing housing.

Financing Implications

SB 9:
Two-unit (no split) avoids OO covenant; lot split adds 3-year OO covenant.

SB 684:
Build as condos or townhomes. No restrictions on end user buyers.

SB 330:
Reduces risk of midstream rule/ fee changes.

Checklists

SB 9 — Two-Unit (No Lot Split)

Confirm parcel SB 9 eligibility (not in historic district, wetlands, hazardous waste, or in very high fire hazard zones, hazard/services OK; no tenant occupancy within 3 years).
Align design with state and local standards (may include ≤1 parking per unit unless exempt; observe 4-ft setbacks; ensure 800 sf minimum protected).
Note expected 30-day rental minimum; confirm local STR rules.

SB 9 — Urban Lot Split

All of the above, plus: execute and record the 3-year owner-occupancy affidavit per city process.
Confirm map eligibility, utilities, access, and separate addresses/ lot compliance. Lot cannot be split if the only access to the lot is from an alley.
Budget for build costs and additional timing; verify any local frontage or utility separation conditions.

SB 684 — Small-Lot Subdivision (≤10 Units)

Verify ‘urbanized area/infill’ status and parcel size; check city’s SB 684/ SB 1123 bulletin for criteria.
Pre-apply with a small-lot site plan meeting local townhouse/rowhome standards; confirm hazard overlays and frontage.
Consider HOA vs no-HOA structure and CCRs early.
Map approval is procedural—sequence tentative/ final maps and building permits to compress hold time.

SB 330 — Housing Crisis Act (Process Shield)

File the SB 330 Preliminary Application early to lock in current standards, regulations and many fees.
Track the hearing count (limit of 5)
If protected units are affected, model replacement and right-to-return obligations.
Pair with SB 9/SB 684/local zoning to create yield; SB 330 alone does not grant additional units.

At Flipside Lending, we’re here to help developers navigate the nuances of project economics and finance deals that make the most sense for your strategy.

Have questions about which type of financing is right for your deal? Let’s talk.

You can reach me at mmiles@flipsideloans.com to learn more.