(2) The school district, not more often than once a year, may levy a tax on the taxable property of the district to pay the warrant interest or principal when due. The taxes shall be collected in the same manner as other school taxes. These warrants shall be sold, and the principal and interest provided for and paid when due in the manner provided by law for bonds issued under this chapter. [Formerly 328.285; 1971 c.513 §63; 1983 c.83 §47; 1991 c.67 §81]