Under regulations prescribed under
section 5738 of this title, an agency shall pay from its appropriations the expenses of round-trip travel of an employee of the Government appointed by the President, by and with the advice and consent of the Senate, for a term fixed by statute, and of transportation of his immediate family, but not household goods, from his post of duty outside the continental United States, Alaska, and Hawaii to the place of his actual residence at the time of appointment to the post of duty, after he has satisfactorily completed each 2 years of service outside the continental United States, Alaska, and Hawaii and is returning to his actual place of residence to take leave before serving at least 2 more years of duty outside the continental United States, Alaska, and Hawaii.