((a)) Each officer of the Regular Coast Guard serving in the grade of lieutenant commander or commander, who has failed of selection for promotion to the grade of commander or captain, respectively, for the second time shall:
((1)) if he has completed at least 20 years of active service or is eligible for retirement under any law on June 30 of the promotion year in which his second failure of selection occurs, be retired on that date; or
((2)) if ineligible for retirement on the date specified in clause (1) 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)) A lieutenant commander or commander of the Regular Coast Guard subject to discharge or retirement under subsection (a) may be continued on active duty when the Secretary directs a selection board convened under to continue up to a specified number of lieutenant commanders or commanders on active duty. When so directed, the selection board shall recommend those officers who in the opinion of the board are best qualified to advance the needs and efficiency of the Coast Guard. When the recommendations of the board are approved by the Secretary, the officers recommended for continuation shall be notified that they have been recommended for continuation and offered an additional term of service that fulfills the needs of the Coast Guard.
((c))
((1)) An officer who holds the grade of lieutenant commander of the Regular Coast Guard may not be continued on active duty under subsection (b) for a period that extends beyond 24 years of active commissioned service unless promoted to the grade of commander of the Regular Coast Guard. An officer who holds the grade of commander of the Regular Coast Guard may not be continued on active duty under subsection (b) for a period that extends beyond 26 years of active commissioned service unless promoted to the grade of captain of the Regular Coast Guard.
((2)) Unless retired or discharged under another provision of law, each officer who is continued on active duty under subsection (b) but is not subsequently promoted or continued on active duty, and is not on a list of officers recommended for continuation or for promotion to the next higher grade, shall, if eligible for retirement under any provision of law, be retired under that law on the first day of the first month following the month in which the period of continued service is completed.