Illinois Bond-Refunding is a process of refinancing the state's existing bond debt to reduce interest costs. Bond-refunding typically involves the issuance of a new bond to replace the old bond, with a lower interest rate. The new bond pays off the old bond, providing a refund to the state or municipality. The state or municipality then uses the refund to lower its short-term or long-term debt. There are two primary types of Illinois Bond-Refunding: traditional refunding and advanced refunding. Traditional refunding involves the replacement of an existing bond with a new one at a lower interest rate. Advanced refunding is a more complex form of bond-refunding that involves the sale of a new bond before the maturity date of the existing bond. The proceeds from the sale of the new bond are used to purchase a US Treasury security, which is then used to pay off the existing bond. This allows for a refund to the state or municipality and a lower interest rate on the new bond.