Neb. Rev. Stat. § 14-2133

Metropolitan utilities districts in rendering bills and statements may set forth therein the net amount that shall be due without setting forth the amount of the discount, if any. When bills are so rendered, the metropolitan utilities district may collect an additional charge of not more than ten percent when bills or statements rendered are not paid at maturity, it being understood that the additional charge is not added by way of penalty but as a means of economizing in bookkeeping and in rendering bills and statements by which the items of discount are omitted therefrom.