Conn. Gen. Stat. § 7-385

All bonds issued under the provisions of this chapter shall mature in annual or semiannual installments of principal that shall substantially equalize the aggregate amount of principal and interest due in each annual period commencing with the first annual period in which an installment of principal is due, or shall mature in annual or semiannual installments of principal no one of which shall exceed by more than fifty per cent the amount of any prior installment. The first installment of principal of any series of bonds shall mature not later than one year from the date of issue of such series and the last installment of such series shall mature not later than twenty years therefrom.