to major or lieutenant commander, if the Secretary concerned determines that such greater number is necessary to maintain or improve medical readiness before the period at the end. 507. Prohibition on appointment or nomination of certain officers who are subject to special selection review boards (a) Officers on active-duty list Section 628a(a)(2)(B) of title 10, United States Code, is amended to read as follows: (B) shall not be forwarded for appointment or nomination to the Secretary of Defense, the President, or the Senate, as applicable. . (b) Officers on reserve active-status list Section 14502a(a)(2)(B) of title 10, United States Code, is amended to read as follows: (B) shall not be forwarded for appointment or nomination to the Secretary of Defense, the President, or the Senate, as applicable. . 508. Effect of failure of selection for promotion (a) Effect of failure of selection for promotion: captains and majors of the Army, Air Force, Marine Corps, and Space Force and lieutenants and lieutenant commanders of the Navy (1) In general Section 632 of title 10, United States Code, is amended— (A) in the section heading, by striking and Marine Corps and inserting Marine Corps, and Space Force