(a) The Assistant Secretary-Indian Affairs will establish a billing cycle that is appropriate to the goods/services being provided.(b) Payment is due within 30 days after the billing date.(c) Upon non-payment by the non-Federal user, the Assistant Secretary may discontinue service. Service may be discontinued after proper notification by letter. Proper notification shall include:(1) Written notice to user that payment is due. Such notice shall afford the user the opportunity to challenge payment or excuse non-payment within 14 days of the date on the notification letter.(2) Following the expiration of the 14 day deadline for response, and after consideration of any such response, the Assistant Secretary-Indian Affairs may notify the user by letter that if payment is not received within 10 days of the date on the letter, the service will be discontinued.(d) The Assistant Secretary has the discretion to continue services for health and safety reasons. However, the non-Federal user is still responsible for payment for goods/services provided.(e) Once service has been discontinued based on delinquency of payment, the discontinuance may be appealed under part 2 of this title.