105 ILCS 5/19-20
The refunding bonds shall be of such form and denomination, payable at such place, bear such date, and be executed by such officials as may be provided by the corporate authorities of the school district in the bond resolution. They shall mature within not to exceed 20 years from their date, and may be made callable on any interest payment date at par and accrued interest after notice has been given at the time and in the manner provided in the bond resolution; however, the limitation shall be 25 years for bonds issued by Valley View Community Unit School District 365U that refund (i) bonds authorized under Section 19-3 of this Code or (ii) bonds refunding or continuing to refund bonds authorized under Section 19-3 of this Code.
105 ILCS 5/19-20