California Code, Government Code - GOV § 43822

If provision is made for the payment of bonds in advance of maturity, the legislative body shall levy and collect a tax which, with any other funds in the treasury set apart for the purpose, is sufficient to pay the portion of such bonds becoming payable before maturity and prior to the time for fixing the next general tax levy. The tax shall be levied and collected annually until all such bonds are paid, or there is a sufficient sum in the city treasury set apart for that purpose to meet all sums due or to become due on the principal of the bonds.