(1) If a notice of violation and penalty order become final in the absence of a request for hearing, the penalty is due within 30 days after the expiration of the period for requesting a hearing.

(2) If an individual named in a notice of violation and penalty order files a request for hearing, the penalty is due within 30 days after the issuance of a final administrative order affirming, increasing, or decreasing the proposed penalty, unless enforcement of the order is stayed pursuant to 2-4-702, MCA.

(3) If the department and the corporate permittee or individual have agreed in writing on a plan for the abatement of the violation, the individual named in the notice of violation and penalty order may postpone payment until receiving either a final order stating that the penalty is due on the date of the final order or a written notice that abatement is satisfactory and the penalty has been withdrawn.

(4) Following the expiration of 30 days after the issuance of a final order assessing an individual civil penalty, any delinquent penalty is subject to interest at the rate established quarterly by the U.S. Department of the Treasury for use in applying late charges on late payments to the federal government, pursuant to Treasury Financial Manual 6-8020.20. The Treasury Current Value of Funds Rate is published by the fiscal service in the notices section of the Federal Register. Interest on unpaid penalties runs from the date payment first was due until the date of payment.

(5) Failure to pay overdue penalties may result in initiation of litigation; reporting to the Department of Revenue, the State Auditor, the Internal Revenue Service, credit bureaus, or to all or any combination of them; or referral to collection agencies. These remedies are not exclusive.

(6) Delinquent penalties are subject to a late payment penalty, in addition to the interest specified in (4), of 6% per annum. This penalty begins to accrue on the 92nd day and runs until the date of payment.

(7) For all delinquent fees, interest and any penalties, the debtor shall pay a processing and handling charge based upon the following components:

(a) for debts referred to a collection agency, the amount charged to the department by the collection agency;

(b) for debts processed and handled by the department, a standard amount set annually by the department based upon similar charges by collection agencies for debt collection. In addition, if the case is referred to the department's attorneys but paid prior to litigation, the estimated average cost to prepare the case for litigation as of the time of payment must also be paid;

(c) for debts referred to the department's attorneys and litigated, the estimated cost to prepare and litigate a debt case as of the time of payment; and

(d) if not otherwise provided for, all other administrative expenses associated with collection, including, but not limited to, billing, recording payments, and follow-up actions.

(8) No prejudgment interest accrues on any processing and handling charges.