Cal. Rev. & Tax. Code § 155

The time fixed in this division for the performance of any act by the assessor or county board may be extended by the board or its executive director for not more than 30 days, or, in case of public calamity, 40 days. If an extension of time is granted, the executive director of the board shall give written notice thereof to the county auditor, county tax collector, and the officer or county board to whom the extension is granted. The executive director shall inform the board at its next regular meeting of any action with respect to extensions taken by him or her. There shall be the same extension of time for any act of the board dependent on the act for which time was extended.