(a) Except an officer of the Navy and Marine Corps who is an officer designated for limited duty (to whom section 8146(e) or 8372 of this title applies) and except as provided under section 637(a) of this title, each officer of the Army, Air Force, or Marine Corps on the active-duty list who holds the grade of captain or major, and each officer of the Navy on the active-duty list who holds the grade of lieutenant or lieutenant commander, who has failed of selection for promotion to the next higher grade for the second time and whose name is not on a list of officers recommended for promotion to the next higher grade shall—

(1) except as provided in paragraph (3) and in subsection (c), be discharged on the date requested by him and approved by the Secretary concerned, which date shall be not later than the first day of the seventh calendar month beginning after the month in which the President approves the report of the board which considered him for the second time;

(2) if he is eligible for retirement under any provision of law, be retired under that law on the date requested by him and approved by the Secretary concerned, which date shall be not later than the first day of the seventh calendar month beginning after the month in which the President approves the report of the board which considered him for the second time; or

(3) if on the date on which he is to be discharged under paragraph (1) he is within two years of qualifying for retirement under section 7311, 8323, or 9311 of this title, be retained on active duty until he is qualified for retirement and then retired under that section, unless he is sooner retired or discharged under another provision of law.

(b) The retirement or discharge of an officer pursuant to this section shall be considered to be an involuntary retirement or discharge for purposes of any other provision of law.

(c)

(1) If a health professions officer described in paragraph (3) is subject to discharge under subsection (a)(1) and, as of the date on which the officer is to be discharged under that subsection, the officer has not completed a period of active duty service obligation that the officer incurred under section 2005, 2114, 2123, or 2603 of this title, the officer shall be retained on active duty until completion of such active duty service obligation, and then be discharged under that subsection, unless sooner retired or discharged under another provision of law.

(2) The Secretary concerned may waive the applicability of paragraph (1) to any officer if the Secretary determines that completion of the active duty service obligation of that officer is not in the best interest of the service.

(3) This subsection applies to a medical officer or dental officer or an officer appointed in a medical skill other than as a medical officer or dental officer (as defined in regulations prescribed by the Secretary of Defense).