Mo. Rev. Stat. § 95.435
Every city or town before issuing such bonds shall provide for a sinking fund to be levied and collected during each year prior to the maturity of any bonds issued under the provisions of sections 95.415 to 95.460, sufficient to provide for the payment of the bonds at maturity, or any interest thereon; and any ordinance authorizing and directing the issue of such bonds shall also provide for a sinking fund for their payment. Such sinking fund shall be provided from the annual revenues and incomes mentioned in section 95.425, if such there be, and from a special tax to be levied annually, sufficient to meet and discharge the maturing bonds and matured or maturing interest; and the city council or other proper legislative body of any such city or town shall be bound and required to levy and collect, during each fiscal year, a special tax sufficient, with the aforesaid revenues and incomes, to pay all interest matured and maturing during that fiscal year, and provide for and keep up the sinking fund as aforesaid.
§ 95.435, RSMo