Yes, if you violate a service agreement (other than for reasons beyond your control and which must be accepted by your agency), you will have incurred a debt due to the Government and you must reimburse all costs that your agency has paid towards your relocation expenses including withholding tax allowance (WTA) and relocation income tax (RIT) allowance.
[FTR Amdt. 98, 66 FR 58196, Nov. 20, 2001. Redesignated by FTR Amdt. 2014-01, 79 FR 49644, Aug. 21, 2014]