(1) A regular officer on the active-duty list of the Army, Navy, Air Force, or Marine Corps may be considered for selective early retirement by a selection board convened under section
611 (b) of this title if the officer is described in any of subparagraphs (A) through (D) as follows:
(A) An officer holding the regular grade of lieutenant colonel or commander who has failed of selection for promotion to the grade of colonel or, in the case of an officer of the Navy, captain two or more times and whose name is not on a list of officers recommended for promotion.
(B) An officer holding the regular grade of colonel or, in the case of an officer of the Navy, captain who has served at least four years of active duty in that grade and whose name is not on a list of officers recommended for promotion.
(C) An officer holding the regular grade of brigadier general or rear admiral (lower half) who has served at least three and one-half years of active duty in that grade and whose name is not on a list of officers recommended for promotion.
(D) An officer holding the regular grade of major general or rear admiral who has served at least three and one-half years of active duty in that grade.
(2) The Secretary of the military department concerned shall specify the number of officers described in paragraphs (1)(A) and (1)(B) which a selection board convened under section
611 (b) of this title may recommend for early retirement. Such number may not be more than 30 percent of the number of officers considered in each grade in each competitive category.
(3) A regular officer on the active-duty list of the Army, Navy, Air Force, or Marine Corps may also be considered for early retirement under the circumstances prescribed in section
638a of this title.