45 CFR §607.8

1. (a)Deductions to liquidate an employee's debt will be by the method and in the amount stated in the Chief Financial Officer's notice of intention to offset as provided in § 607.4. Debts will be collected in one lump sum where possible. If the employee is financially unable to pay in one lump sum, collection must be made in installments.
2. (b)Debts will be collected by deduction at officially established pay intervals from an employee's current pay account unless alternative arrangements for repayment are made.
3. (c)Installment deductions will be made over a period not greater than the anticipated period of employment. The size of installment deductions must bear a reasonable relationship to the size of the debt and the employee's ability to pay. The deduction for the pay intervals for any period must not exceed 15% of disposable pay unless the employee has agreed in writing to a deduction of a greater amount.
4. (d)Unliquidated debts may be offset against any financial payment due to a separated employee including but not limited to final salary or leave payment in accordance with 31 U.S.C. 3716.