31 C.F.R. § 5.5

(a) Assessment and notice. Treasury entities shall assess interest, penalties and administrative costs on Treasury debts in accordance with the provisions of 31 U.S.C. 3717 and 31 CFR 901.9, on Treasury debts. Interest shall be charged in accordance with the requirements of 31 U.S.C. 3717(a). Penalties shall accrue at the rate of 6% per year, or such other higher rate as authorized by law. Administrative costs, that is the costs of processing and handling a delinquent debt, shall be determined by the Treasury entity collecting the Treasury debt. Treasury entities may have additional policies regarding how interest, penalties, and administrative costs are assessed on particular types of debts. Treasury entities are required to explain in the notice to the debtor described in § 5.4 of this part how interest, penalties, costs, and other charges are assessed, unless the requirements are included in a contract or repayment agreement.

(b) Waiver of interest, penalties, and administrative costs. Unless otherwise required by law, Treasury entities may not charge interest if the amount due on the debt is paid within 30 days after the date from which the interest accrues. See 31 U.S.C. 3717(d). Treasury entities may waive interest, penalties, and administrative costs, or any portion thereof, when it would be against equity and good conscience or not in the Treasury entity's best interest to collect such charges, in accordance with Treasury guidelines for waiving claims against Treasury employees for erroneous overpayments. See Treasury Directive 34-01 (Waiving Claims Against Treasury Employees for Erroneous Payments) set forth at appendix A of this part and at http://www.treas.gov/regs. Legal counsel approval is not required to waive such charges. Cf., §§ 5.7 and 5.8 of this part, which require legal counsel approval when compromising a debt or terminating debt collection activity on a debt.

(c) Accrual during suspension of debt collection. In most cases, interest, penalties and administrative costs will continue to accrue during any period when collection has been suspended for any reason (for example, when the debtor has requested a hearing). Treasury entities may suspend accrual of any or all of these charges when accrual would be against equity and good conscience or not in the Treasury entity's best interest, in accordance with Treasury guidelines for waiving claims against Treasury employees for erroneous overpayments. See Treasury Directive 34-01 (Waiving Claims Against Treasury Employees for Erroneous Payments), set forth at appendix A of this part and http://www.treas.gov/regs.