January 1, 2020 was the statewide effective date established by the California Building Standards Commission (CBSC) for the 2019 California Building Standards Code which adopts the 2018 editions of the IBC, IFC, IRC and IEBC with amendments.
January 1, 2023 is the effective date for the 2022 California Building Standards Code which adopts the 2021 editions of the IBC, IFC, IRC and IEBC with amendments.
The California Codes can be viewed here.
Please also see California Code Adoption Resources
Links to State Adoption Agencies
ICC Government Relations Representative
California Building Standards Commission: