A debt will be collected in a lump-sum or in installments. Collection will be by lump-sum collection unless the employee is financially unable to pay in one lump-sum, or if the amount of the debt exceeds 15 percent of the disposable pay for an ordinary pay period. In these cases, deduction will be by installments as set forth in Sec. 400.138. [53 FR 5, Jan. 4, 1988]