Advance refunding bong permits an issuer to get the advantage of lower interest rates when the due bonds are not at present callable. The proceeds from the sale of the refunding bonds are made use to buy taxable government securities that are put in an escrow account. The escrow account is planned so that the principal and interest earned on the securities are enough to pay all principal, interest, and other call premium, if any, on the outstanding bonds up to and counting the call date. The refunding bonds are protected by the same sources of taxes or revenue before pledged to the payment of the outstanding bonds.