(a) Interest. EPA will assess interest on all delinquent debts unless prohibited by statute, regulation or contract.

(1) Interest begins to accrue on all debts from the date of the initial notice to the debtor. EPA will not recover interest where the debt is paid within 30 days of the date of the notice. EPA will assess an annual rate of interest that is equal to the rate of the current value of funds to the United States Treasury (i.e., the Treasury tax and loan account rate) as prescribed and published by the Secretary of the Treasury in the Federal Register and the Treasury Fiscal Requirements Manual Bulletins, unless a different rate is necessary to protect the interest of the Government. EPA will notify the debtor of the basis for its finding that a different rate is necessary to protect the interest of the Government.

(2) The Administrator may extend the 30-day period for payment where he determines that such action is in the best interest of the Government. A decision to extend or not to extend the payment period is final and is not subject to further review.

(3) The rate of interest, as initially assessed, remains fixed for the duration of the indebtedness. If a debtor defaults on a repayment agreement, interest may be set at the Treasury rate in effect on the date a new agreement is executed.

(4) Interest will not be assessed on interest charges, administrative costs or later payment penalties. However, where a debtor defaults on a previous repayment agreement and interest, administrative costs and penalties charges have been waived under the defaulted agreement, these charges can be reinstated and added to the debt principal under any new agreement and interest charged on the entire amount of the debt.

(b) Administrative costs of collecting overdue debts. The costs of the Agency's administrative handling of overdue debts, based on either actual or average cost incurred, will be charged on all debts except those owed by State and local governments and Indian tribes. These costs include both direct and indirect costs. Administrative costs will be assessed monthly throughout the period the debt is overdue except as provided by §13.12.

(c) Penalties. As provided by 31 U.S.C. 3717(e)(2), a penalty charge will be assessed on all debts, except those owned by State and local governments and Indian tribes, more than 90 days delinquent. The penalty charge will be at a rate not to exceed 6% per annum and will be assessed monthly.

(d) Allocation of payments. A partial payment by a debtor will be applied first to outstanding administrative costs, second to penalty assessments, third to accrued interest and then to the outstanding debt principal.

(e) Waiver.

(1) The Administrator may (without regard to the amount of the debt) waive collection of all or part of accrued interest, penalty or administrative costs, where he determines that—

(i) Waiver is justified under the criteria of §13.25;

(ii) The debt or the charges resulted from the Agency's error, action or inaction, and without fault by the debtor; or

(iii) Collection of these charges would be against equity and good conscience or not in the best interest of the United States.

(2) A decision to waive interest, penalty charges or administrative costs may be made at any time prior to payment of a debt. However, where these charges have been collected prior to the waiver decision, they will not be refunded. The Administrator's decision to waive or not waive collection of these charges is a final agency action.