Rule 38.5.901 - DEFINITION(1) "Billing error" means any bill issued by a natural gas, electric, private water or sewer utility that is not designated as an estimate and that understates the amount owed by a utility customer. It also means a utility's failure to bill a customer, although there was energy consumption which would, under the utility's normal billing practices, be billed to the customer.NEW, 1983 MAR p. 1739, Eff. 11/26/83.Sec. 69-3-103, MCA; IMP, Sec. 69-3-102, MCA;