Illinois Statutes Chapter 50. Local Government § 460/20. Additional costs allowed

(a) an additional reserve, not to exceed 10% of the amount of the bonds issued pursuant to this Act, as a reserve for the payment of interest on or principal of bonds when due in the event of nonpayment of any assessments; provided however, the interest earnings, if any, on the additional reserve shall be applied to the next installment as a partial reduction of payment due;

(b) an amount for the payment of interest upon bonds for a period not to exceed the greater of 2 years or a period ending 6 months after the estimated date of completion of the acquisition and construction of the local improvement that is the subject of the special assessment proceeding; and

(c) an amount for bond discount (the difference between the face amount of a bond and the price at which the bond is to be sold, exclusive of original issue discount) not to exceed 4% of the total cost of the improvement. The reserve provided for by clause (a) of this Section shall be in addition to and in excess of any other reserve otherwise permitted by special assessment law including reserves for interest deficiencies. Any additional cost or reserve to be included by authority of this Section shall be expressly provided for in the special assessment ordinance and shall further be expressly stated in any engineer's estimate of cost prepared in connection with a special assessment ordinance as provided by a special assessment law.