If you do not have an approved exception under § 301-50.4 or § 301-73.104 of this chapter, you are responsible for any additional costs resulting from the failure to use the TMS or E-Gov Travel Service, including service fees, cancellation penalties, or other additional costs (e.g., higher airfares, rental car charges, or hotel rates). In addition, your agency may take appropriate disciplinary action.
41 C.F.R. §301-50.5