105 ILCS 5/19-16
The corporate authorities of any school district, without submitting the question to the electors thereof for approval, may authorize by resolution the issuance of refunding bonds (1) to refund its bonds prior to their maturity; (2) to refund its unpaid matured bonds; (3) to refund matured coupons evidencing interest upon its unpaid bonds; (4) to refund interest at the coupon rate upon its unpaid matured bonds that has accrued since the maturity of those bonds; (5) to refund its bonds which by their terms are subject to redemption before maturity; and (6) to refund other valid and subsisting evidences of indebtedness that are due and payable. The refunding bonds and the procedure for issuing them shall comply with Sections 19--5 through 19--7.
105 ILCS 5/19-16