Not later than August 1st of each year, the board of administration of any retirement plan established under the provisions of this chapter, shall file with the board of supervisors a written statement showing the amounts necessary to be provided by the county during the current fiscal year for the maintenance of the peace officers and fire service retirement fund and administration expense. Such statement shall be filed with said board not less than thirty days prior to the time established by law for the annual levying of taxes in such county.