California Code, Government Code - GOV § 29923

The tax for interest and redemption of bonds shall be in addition to all other taxes, and shall not be less than sufficient to pay the interest on the bonds and such portion of the principal, if any, as is to become due before the time for making the next general tax levy. It shall also be sufficient to constitute a sinking fund for the payment of the principal of the bonds on or before maturity. The board shall provide for the levy of an annual tax sufficient to effect the objects of this section either in the resolution providing for the issuance of the bonds or in an ordinance adopted before or at the time of issuing the bonds.