Yes, if you are an employee of an agency as defined in § 301-1.1 of this chapter, you must use the ETS, or your agency's TMS (if an exception to ETS use is granted), to make your travel arrangements. If you are an employee of the Department of Defense, the legislative branch, or the Government of the District of Columbia, you must arrange your travel in accordance with your agency's TMS. Your agency may grant, or be granted, an exception to required use of TMS or ETS under § 301-50.4 or § 301-73.102 or § 301-73.104 of this chapter.
41 C.F.R. §§301-50.3