41 C.F.R. § 302-2.4
Penalties for violation of service agreement
If the employee violates a service agreement (other than for reasons beyond their control and which must be accepted by the agency), the employee will have incurred a debt due to the Government and must reimburse all costs that the agency has paid towards the relocation expenses including withholding tax allowance (WTA) and relocation income tax allowance (RITA).