Except as provided in paragraph (6), a commissioned officer retired pursuant to paragraph (1), (2), or (3) who was (in the case of an officer in the Reserve Corps) on active duty with the Service on the day preceding such retirement shall be entitled to receive retired pay calculated by multiplying the retired pay base determined under section 1406 of title 10 by the retired pay multiplier determined under section 1409 of such title for the numbers of years of service credited to the officer under this paragraph and in which, in the case of a temporary promotion to such grade, he has performed active duty for not less than six months, (A) for each year of active service, or (B) if it results in higher retired pay, for each of the following years:

(1) A commissioned officer of the Service shall, if he applies for retirement, be retired on or after the first day of the month following the month in which he attains the age of sixty-four years. This paragraph does not permit or require the involuntary retirement of any individual because of the age of the individual.

(2) A commissioned officer of the Service may be retired by the Secretary, and shall be retired if he applies for retirement, on the first day of any month after completion of thirty years of active service.

(3) Any commissioned officer of the Service who has had less than thirty years of active service may be retired by the Secretary, with or without application by the officer, on the first day of any month after completion of twenty or more years of active service of which not less than ten are years of active commissioned service in any of the uniformed services.

(4) Except as provided in paragraph (6), a commissioned officer retired pursuant to paragraph (1), (2), or (3) who was (in the case of an officer in the Reserve Corps) on active duty with the Service on the day preceding such retirement shall be entitled to receive retired pay calculated by multiplying the retired pay base determined under section 1406 of title 10 by the retired pay multiplier determined under section 1409 of such title for the numbers of years of service credited to the officer under this paragraph and in which, in the case of a temporary promotion to such grade, he has performed active duty for not less than six months, (A) for each year of active service, or (B) if it results in higher retired pay, for each of the following years: (i) his years of active service (determined without regard to subsection (d)) as a member of a uniformed service; plus (ii) in the case of a medical or dental officer, four years and, in the case of a medical officer, who has completed one year of medical internship or the equivalent thereof, one additional year, the four years and the one year to be reduced by the period of active service performed during such officer’s attendance at medical school or dental school or during his medical internship; plus (iii) the number of years of service with which he was entitled to be credited for purposes of basic pay on May 31, 1958, or (if higher) on any date prior thereto, reduced by any such year included under clause (i) and further reduced by any such year with which he was entitled to be credited under paragraphs (7) and (8) of section 205(a) of title 37 on any date before June 1, 1958; except that (C) in the case of any officer whose retired pay, so computed, is less than 50 per centum of such basic pay, who retires pursuant to paragraph (1) of this subsection, who has not less than twelve whole years of active service (computed without the application of subsection (e)), and who does not use, for purposes of a retirement annuity under subchapter III of chapter 83 of title 5, any service which is also creditable in computing his retired pay from the Service, it shall, instead, be 50 per centum of such pay, (D) the retired pay of an officer shall in no case be more than 75 per centum of such basic pay, and (E) in the case of any officer who participates in the modernized retirement system by reason of section 1409(b) of title 10 (including pursuant to an election under subparagraph (B) of that section), subparagraph (C) shall be applied by substituting “40 per centum” for “50 per centum” each place the term appears.

(5) With the approval of the President, a commissioned officer whose service as Surgeon General, Deputy Surgeon General, or Assistant Surgeon General has totaled four years or more and who has had not less than twenty-five years of active service in the Service may retire voluntarily at any time; and except as provided in paragraph (6), his retired pay shall be at the rate of 75 per centum of the basic pay of the highest grade held by him as such officer.

The retired pay of a commissioned officer retired under this subsection who first became a member of a uniformed service after September 7, 1980, is determined by multiplying—

(A) the retired pay base determined under section 1407 of title 10; by

(B) the retired pay multiplier determined under section 1409 of such title for the number of years of service credited to the officer under paragraph (4).

(7) Retired pay computed under section 211(g)(3) of this title or under paragraph (4) or (5) of this subsection, if not a multiple of $1, shall be rounded to the next lower multiple of $1.

For purposes of subsection (a), the basic pay of the highest grade to which a commissioned officer has received a temporary promotion means the basic pay to which he would be entitled if serving on active duty in such grade on the date of his retirement.

A commissioned officer, retired for reasons other than for failure of promotion to the senior grade, may (1) if an officer of the Regular Corps or an officer of the Reserve Corps entitled to retired pay under subsection (a), be involuntarily recalled to active duty during such times as the Commissioned Corps constitutes a branch of the land or naval forces of the United States, and (2) if an officer of either the Regular or Reserve Corps, be recalled to active duty at any time with his consent.

The term “active service”, as used in subsection (a), includes:

(1) all active service in any of the uniformed services;

(2) active service with the Public Health Service, other than as a commissioned officer, which the Surgeon General determines is comparable to service performed by commissioned officers of the Service, except that, if there are more than five years of such service only the last five years thereof may be in­cluded;

(3) all active service (other than service included under the preceding provisions of this subsection) which is creditable for retirement purposes under laws governing the retirement of members of any of the uniformed services; and

(4) service performed as a member of the Senior Biomedical Research Service established by section 237 of this title, except that, if there are more than 5 years of such service, only the last 5 years thereof may be included.

For the purpose of determining the number of years by which a percentage of the basic pay of an officer is to be multiplied in computing the amount of his retired pay pursuant to section 211(g)(3) of this title or paragraph (4) of subsection (a) of this section, each full month of service that is in addition to the number of full years of service credited to an officer is counted as one-twelfth of a year and any remaining fractional part of a month is dis­regarded.

For purposes of retirement or separation for physical disability under chapter 61 of title 10, a commissioned officer of the Service shall be credited, in addition to the service described in section 1208(a)(2) of that title, with active service with the Public Health Service, other than as a commissioned officer, which the Surgeon General determines is comparable to service performed by commissioned officers of the Service, except that, if there are more than five years of such service, only the last five years thereof may be so credited. For such purposes, such section 1208(a)(2) shall be applicable to officers of the Regular or Reserve Corps of the Service.

(July 1, 1944, ch. 373, title II, § 211, 58 Stat. 688; Feb. 28, 1948, ch. 83, § 7, 62 Stat. 46; Oct. 12, 1949, ch. 681, title V, § 521(d), 63 Stat. 835; 1953 Reorg. Plan No. 1, §§ 5, 8, eff. Apr. 11, 1953, 18 F.R. 2053, 67 Stat. 631; Apr. 27, 1956, ch. 211, § 5(a)–(c), 70 Stat. 117; Aug. 10, 1956, ch. 1041, § 5, 70A Stat. 620; Pub. L. 86–415, § 4, Apr. 8, 1960, 74 Stat. 33; Pub. L. 91–253, § 1, May 14, 1970, 84 Stat. 216; Pub. L. 96–76, title III, § 308, Sept. 29, 1979, 93 Stat. 585; Pub. L. 96–342, title VIII, § 813(h)(2), Sept. 8, 1980, 94 Stat. 1110; Pub. L. 97–25, title III, § 303(b), July 27, 1981, 95 Stat. 145; Pub. L. 97–35, title XXVII, § 2765(a), Aug. 13, 1981, 95 Stat. 932; Pub. L. 98–94, title IX, §§ 922(d), 923(f), Sept. 24, 1983, 97 Stat. 642, 643; Pub. L. 99–348, title II, § 207(b), July 1, 1986, 100 Stat. 702; Pub. L. 101–509, title V, § 529 [title III, § 304(b)], Nov. 5, 1990, 104 Stat. 1427, 1464; Pub. L. 114–92, div. A, title VI, § 631(c)(4), Nov. 25, 2015, 129 Stat. 845.)