31 CFR § 901.8 - Collection in installments.
(a) Whenever feasible, agencies shall collect the total amount of a debt in one lump sum. If a debtor is financially unable to pay a debt in one lump sum, agencies may accept payment in regular installments. Agencies should obtain financial statements from debtors who represent that they are unable to pay in one lump sum and independently verify such representations whenever possible (see § 902.2(g) of this chapter). Agencies that agree to accept payments in regular installments should obtain a legally enforceable written agreement from the debtor that specifies all of the terms of the arrangement and that contains a provision accelerating the debt in the event of default.
(b) The size and frequency of installment payments should bear a reasonable relation to the size of the debt and the debtor's ability to pay. If possible, the installment payments should be sufficient in size and frequency to liquidate the debt in three years or less.
(c) Security for deferred payments should be obtained in appropriate cases. Agencies may accept installment payments notwithstanding the refusal of the debtor to execute a written agreement or to give security, at the agency's option.