31 C.F.R. § 29.520
The Department may refer to the Justice Department for litigation overpayment debts which cannot be compromised or waived, or on which collection activity cannot be suspended or terminated, and which the Department has been unable to recover pursuant to the collection activity described in §§ 29.511 through 29.519 . (See 31 CFR part 904 .) Such debts should be referred to the Justice Department as early as possible, but at least within 1 year of the date such debts last became delinquent. In the case of overpayments arising from fraud, misrepresentation, or the presentation of a false claim, referral should be made to the Justice Department immediately. (See 31 CFR 900.3(a) .) Referral of a debt to the Justice Department will suspend processing under §§ 29.511 through 29.519 of this subpart.
31 C.F.R. §29.520