Code of Federal Regulations Title 41. Public Contracts and Property Management § 41.301–71.105 Must we issue a written or electronic travel authorization in advance of travel?

(a) Use of other than coach-class service accommodation on common carriers or use of other than lowest first-class accommodation on ships;

(b) Use of a foreign air carrier;

(c) Use of reduced fares for group or charter arrangements;

(d) Use of cash to pay for common carrier transportation;

(e) Use of extra-fare train service;

(f) Travel by ship;

(g) Use of a rental car;

(h) Use of a Government aircraft;

(i) Payment of a reduced rate per diem;

(j) Payment of actual expenses (see § 301–70.201 for when you may issue a blanket actual expense authorization);

(k) Travel expenses related to emergency travel;

(l) Transportation expenses related to threatened law enforcement/investigative employees and members of their immediate families;

(m) Travel expenses related to travel to a foreign area, except as provided by agency mission;

(n) Acceptance of payment from a non–Federal source for travel expenses (see chapter 304 of this title);  and

(o) Travel expenses related to attendance at a conference.