All obligations issued pursuant to Section 21-41-41 shall mature not longer than twenty (20) years from the date thereof, and shall be divided into approximately equal payments, with one (1) payment falling due each year. The obligations shall bear interest at a rate not exceeding that allowed in Section 75-17-101, payable annually or semiannually, and principal and interest on same shall be payable at such place within or without the state as may be designated by the issuing authorities at the time the obligations are issued. The full faith, credit and resources of the issuing municipality shall be pledged for the payment of the principal and interest on the obligations and the governing authorities of the municipality shall annually levy a tax on all taxable property in the municipality sufficient for such purposes, and where the obligations are issued for the purpose of making any of the special improvements set forth in this chapter, the cost of which is to be paid from assessments levied against the property abutting on the special improvement to be made under this chapter, the assessments shall also be pledged for the payment of the obligations. The funds derived from the taxes levied to pay the obligations shall be kept in a special fund to be known as the “Special Improvement Bond Fund,” and shall be used only for the purpose of paying principal and interest on the obligations. All funds derived from special assessments levied against the property abutting on the special improvements shall likewise be placed into the Special Improvement Bond Fund and shall be used only for the purpose of paying principal and interest on the obligations. Any surplus funds may be invested as provided by law, and may be used to pay the obligations at or before maturity.