((a)) Each officer of the Regular Coast Guard appointed under who is serving in the grade of lieutenant and who has failed of selection for promotion to the grade of lieutenant commander for the second time shall:
((1)) be honorably discharged on June 30 of the promotion year in which his second failure of selection occurs; or
((2)) if he so requests, be honorably discharged at an earlier date without loss of benefits that would accrue if he were discharged on that date under clause (1); or
((3)) if, on the date specified for his discharge in this section, he has completed at least 20 years of active service or is eligible for retirement under any law, be retired on that date; or
((4)) if, on the date specified for his discharge in clause (1), he has completed at least eighteen years of active service, be retained on active duty and retired on the last day of the month in which he completes twenty years of active service, unless earlier removed under another provision of law.
((b))
((1)) When the needs of the service require, the Secretary may direct a selection board, which has been convened under , to recommend for continuation on active duty for terms of not less than two nor more than four years a designated number of officers of the grade of lieutenant who would otherwise be discharged or retired under this section. When so directed, the board shall recommend for continuation on active duty those officers under consideration who are, in the opinion of the board, best qualified for continuation. Each officer so recommended may, with the approval of the Secretary, and notwithstanding subsection (a), be continued on active duty for the term recommended.
((2)) Upon the completion of a term under paragraph (1), an officer shall, unless selected for further continuation—
((A)) except as provided in subparagraph (B), be honorably discharged with separation pay computed under ;
((B)) in the case of an officer who has completed at least 18 years of active service on the date of discharge under subparagraph (A), be retained on active duty and retired on the last day of the month in which the officer completes 20 years of active service, unless earlier removed under another provision of law; or
((C)) if, on the date specified for the officer’s discharge under this section, the officer has completed at least 20 years of active service or is eligible for retirement under any law, be retired on that date.
((c)) Each officer who has been continued on active duty under subsection (b) shall, unless earlier removed from active duty, be retired on the last day of the month in which he completes twenty years of active service.