34 CFR §30.61

1. (a)If a debtor does not make a payment on a debt, or portion of a debt, within 90 days after the date specified in the first demand for payment sent to the debtor, the Secretary imposes a penalty on the debtor.
2. (b)
   1. (1)The amount of the penalty imposed under paragraph (a) of this section is 6 percent per year of the amount of the delinquent debt.
   2. (2)The penalty imposed under this section runs from the date specified in the first demand for payment to the date the debt (including the penalty) is paid.
3. (c)If a debtor has agreed under a repayment or settlement agreement with the Secretary to pay a penalty for failure to pay a debt when due, or has such an agreement under a grant or contract under which the debt arose, the Secretary collects the penalty in accordance with the agreement, grant, or contract.
4. (d)The Secretary does not impose a penalty against State or local governments under paragraphs (a) and (b) of this section.