40 C.F.R. § 13.29
The Administrator may suspend the Agency's collection actions on a debt where the outstanding debt principal does not exceed $20,000, the Government cannot presently collect or enforce collection of any significant sum from the debtor, the prospects of future collection justify retention of the debt for periodic review and there is no risk of expiration of the statute of limitations during the period of suspension. Additionally, the Administrator may waive the assessment of interest, penalty charges and administrative costs during the period of the suspension. Suspension will be for an established time period and generally will be reviewed at least every six months to ensure the continued propriety of the suspension. DOJ approval is required to suspend debts exceeding $20,000. Unless otherwise provided by DOJ delegations or procedures, the Administrator refers requests for suspension of debts of $20,000 to $100,000 to the United States Attorney in whose district the debtor resides. Debts exceeding $100,000 are referred to the Commercial Litigation Branch, Civil Division, Department of Justice, for approval.
40 C.F.R. § 13.29