Senate Bill 9, which takes effect January 1, 2022 requires communities across California to allow duplexes, and in some cases four units, in most single-family home neighborhoods in Senate Bill 9.   Senate Bill 10, also effective January 1, enables cities that want to opt in to upzone urbanized areas close to transit, allowing up to 10 units per parcel without any environmental review or public hearing. 
    

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