Cal. Rev. & Tax. Code § 20810

A county may elect to participate in the County Deferred Property Tax Program for Senior Citizens and Disabled Citizens by adopting a resolution indicating the county’s intention to participate in and to administer the program. All requirements of a county or county officials set forth in this chapter are conditioned upon the county’s adoption of this resolution. Under this program, a participating county may defer a claimant’s property taxes retroactively, for property taxes due on or before February 20, 2011, and prospectively, as provided in this part.