SB 9 Urban Lot Split

What is SB 9?

Senate Bill (SB) 9, signed into law on September 16, 2021, allows for “ministerial approval” of up to two primary dwelling units on a single-family lot. Alternatively, it also allows for splitting a parcel zoned for single-family development into two separate legal parcels, and the construction of up to two units on each resulting parcel.  Ministerial approval is approval given at the staff level that only requires a project conform with a fixed standard or objective measurement and requires no discretionary oversight or judgment of the project.

The Town adopted Chapter 17.53 “Regulations and Objective Standards for Urban Lot Splits and Development Projects Sought Pursuant to Government Code Sections 65852.21 and 66411.7” as part of the Atherton Municipal Code (AMC). 

What exactly does SB 9 allow me to do? 

SB 9 allows property owners to add units to their property in two different ways: 

  1. SB 9 allows up to two units on a parcel so property owners can add a single unit to an existing unit or construct two new units on a vacant parcel
  2. SB 9 allows parcels to be split into separate parcels, each of which may have up to two units (including existing and new units).


SB 9 Eligibility Checklist

SB 9 Lot Split - Affidavit of Intent to Occupy - LLC Owner

SB 9 Lot Split - Affidavit of Intent to Occupy - Private Owner

SB 9 Tentative Map Checklist

SB 9 Final Map Checklist

SB 9 Final Map Recordation Instructions 

SB9 Projects 

Project TypeSite AddressStatus
SB9 Lot Split2 Lowery DrRECORDED
SB9 Lot Split
125 Glenwood AveRECORDED
SB9 Lot Split
94 Palmer LnRECORDED
SB9 Lot Split
78 Cebalo LnRECORDED
SB9 Lot Split
1 Gresham LnRECORDED
SB9 Lot Split
97 Santiago AveRECORDED
SB9 Lot Split
SB9 Lot Split
197 Glenwood AveUNDER REVIEW
SB9 Lot Split

Please review the County recorder's GIS Property Information Portal for information and details of the recorded maps.