(a) When the report of a selection board convened under this chapter is approved by the Secretary concerned, the Secretary shall place the names of the warrant officers approved for promotion on a single promotion list for each grade (or grade and competitive category), in the order of the seniority of such officers on the warrant officer active-duty list.

(b) Promotions of warrant officers on the warrant officer promotion list shall be made when, in accordance with regulations issued by the Secretary concerned, additional warrant officers in that grade (or grade and competitive category), are needed.

(c) A regular warrant officer who is promoted is appointed in the regular grade to which promoted, and a reserve warrant officer who is promoted is appointed in the reserve grade to which promoted. The date of appointment in that grade and date of rank shall be prescribed by the Secretary concerned. A warrant officer is entitled to the pay and allowances for the grade to which appointed from the date specified in the appointment order.

(d) Promotions shall be made in the order in which the names of warrant officers appear on the promotion list and after warrant officers previously selected for promotion in the applicable grade (or grade and competitive category) have been promoted.

(e) A warrant officer who is appointed to a higher grade under this section is considered to have accepted such appointment on the date on which the appointment is made unless the officer expressly declines the appointment.

(f) A warrant officer who has served continuously as an officer since subscribing to the oath of office prescribed in section 3331 of title 5 is not required to take a new oath upon appointment to a higher grade under this section.