Unless otherwise provided by law, the authority and duties of the county board of supervisors with respect to adopting tax rates and levying of taxes prescribed in this article shall have application to school districts and to special districts, or zones or improvement districts thereof, whose affairs and finances are not under the supervision and control of the county board of supervisors but for which a tax levy is carried on the regular county assessment roll.
If the assessed value of the taxable property in a special district on the unsecured roll exceeds the assessed value of the taxable property on the secured roll, the special district tax rate which is adopted by the board for the secured roll shall be adjusted to an amount which the board determines will meet the estimated annual revenue requirements of the district for both the current and the next succeeding year.