California Code, Revenue and Taxation Code - RTC § 123

(a) The amount of taxes which were a lien on the real estate at the time of the declaration of default.

(b) All other unpaid taxes of every description which were a lien on the property for the year of declaration of default and for each year since the declaration of default, as shown on the delinquent rolls for which the time of the declaration of default is past, or, if the property was not assessed for any year, which would be shown on such delinquent roll if it had been assessed in that year; except that the unpaid taxes which would be shown on such delinquent roll if the property had been assessed in any such year shall not be paid if the property was not assessed for any year because of having been acquired by the state or other public agency other than by tax deed. The amount of taxes for any year not assessed shall be based on the valuation required to be made by the assessor on redemption of unassessed property.