Any county, municipality, or political subdivision of this state which incurs an indebtedness under Code Sections 36-80-10 through 36-80-13 and this Code section shall, on or before so doing, or annually thereafter, provide, without incurring further debt thereby, an annual sum sufficient in amount to pay the principal and interest of the debt within 30 years from the date of the incurring of the indebtedness.