(a) Transfer of officers to retired list; separation from service As recommended by a personnel board convened under section 3022 of this title - (1) an officer in the permanent grade of captain or commander may be transferred to the retired list; and (2) an officer in the permanent grade of lieutenant commander, lieutenant, or lieutenant (junior grade) who is not qualified for retirement may be separated from the service. (b) Computations In any fiscal year, the total number of officers selected for retirement or separation under subsection (a) of this section plus the number of officers retired for age may not exceed the whole number nearest 4 percent of the total number of officers authorized to be on the active list, except as otherwise provided by law. (c) Effective date of retirements and separations A retirement or separation under subsection (a) of this section shall take effect on the first day of the sixth month beginning after the date on which the Secretary approves the retirement or separation, except that if the officer concerned requests an earlier retirement or separation date, the date shall be as determined by the Secretary.