41 CFR § 301-73.105
What are the consequences of an employee not using the E-Gov Travel Service or the TMS?
June 9, 2020
If an employee does not use the ETS (when available) or your agency's designated TMS, he/she is responsible for any additional costs (see §301-50.5 of this chapter) resulting from the failure to use the ETS or your TMS. In addition, you may take appropriate disciplinary actions.
[FTR Amdt. 2003-07, 68 FR 71030, Dec. 22, 2003, as amended by FTR Amdt. 2007-05, 72 FR 61540, Oct. 31, 2007]