Gov. Code, § 25105.5

The clerk of the board of supervisors may, without complying with any other provision of law, destroy records consisting of claims against the county and claims against special districts for which the board of supervisors is the governing body, whenever the claims have been retained by the clerk for a period of not less than five years after final action on the claim. The clerk of the board of supervisors may destroy records consisting of assessment appeal applications when five years have elapsed since the final action on the application. The clerk may destroy the records three years after the final action on the application, if the records consisting of assessment appeal applications have been microfilmed, microfiched, imaged, or otherwise preserved on a medium that provides access to the documents, in accordance with Section 25105.

As used in this section “final action” means, in the case of an assessment appeals application, the date of the final decision by the assessment appeals board and, in the case of a claim, the date of payment or settlement of the claim, or denial or approval of the claim by or in behalf of the board of supervisors or by operation of law, whichever occurs first, if there is no action pending involving the application or claim.