(a) Prohibition on Recomputation To Reflect Increases in Basic Pay.—Unless otherwise specifically provided by law, the retired pay of a member or former member of an armed force may not be recomputed to reflect any increase in the rates of basic pay for members of the armed forces.

(b) Cost-of-Living Adjustments Based on CPI Increases.—

(1) Increase required.—Effective on December 1 of each year, the Secretary of Defense shall increase the retired pay of members and former members entitled to that pay in accordance with paragraphs (2) and (3).

(2) Percentage increase.—Except as otherwise provided in this subsection, the Secretary shall increase the retired pay of each member and former member by the percent (adjusted to the nearest one-tenth of 1 percent) by which—

(A) the price index for the base quarter of that year, exceeds

(B) the base index.

(3) Reduced percentage for certain post-august 1, 1986 members.—If the percent determined under paragraph (2) is greater than 1 percent, the Secretary shall increase the retired pay of each member and former member who first became a member on or after August 1, 1986, and has elected to receive a bonus under section 322 (as in effect before the enactment of the National Defense Authorization Act for Fiscal Year 2008) or section 354 of title 37, by the difference between—

(A) the percent determined under paragraph (2); and

(B) 1 percent.

(4) Special rule for paragraph (3).—If in any case in which an increase in retired pay that would otherwise be made under paragraph (3) is not made by reason of law (other than any provision of this section), then (unless otherwise provided by law) when the next increase in retired pay is made under this subsection, the increase under paragraph (3) shall be carried out so as to achieve the same net increase in retired pay under that paragraph that would have been the case if that law had not been enacted.

(5) Adjustments for participants in modernized retirement system.—Notwithstanding paragraph (3), if a member or former member participates in the modernized retirement system by reason of section 1409(b)(4) of this title (including pursuant to an election under subparagraph (B) of that section), the Secretary shall increase the retired pay of such member in accordance with paragraph (2).

(6) Regulations.—Any increase in retired pay under this subsection shall be made in accordance with regulations prescribed by the Secretary of Defense.

(c) First COLA Adjustment for Members With Retired Pay Computed Using Final Basic Pay.—

(1) First adjustment with intervening increase in basic pay.—Notwithstanding subsection (b) but subject to subsection (f)(3), if a person described in paragraph (3) becomes entitled to retired pay based on rates of monthly basic pay that became effective after the last day of the calendar quarter of the base index, the retired pay of the member or former member shall be increased on the effective date of the next adjustment of retired pay under subsection (b) only by the percent (adjusted to the nearest one-tenth of 1 percent) by which—

(A) the price index for the base quarter of that year, exceeds

(B) the price index for the calendar quarter immediately before the calendar quarter in which the rates of monthly basic pay on which the retired pay is based became effective.

(2) First adjustment with no intervening increase in basic pay.—If a person described in paragraph (3) becomes entitled to retired pay on or after the effective date of an adjustment in retired pay under subsection (b) but before the effective date of the next increase in the rates of monthly basic pay, the retired pay of the member or former member shall be increased (subject to subsection (f)(3) as applied to other members whose retired pay is computed on the current rates of basic pay in the most recent adjustment under this section), effective on the date the member becomes entitled to that pay, by the percent (adjusted to the nearest one-tenth of 1 percent) by which—

(A) the base index, exceeds

(B) the price index for the calendar quarter immediately before the calendar quarter in which the rates of monthly basic pay on which the retired pay is based became effective.

(3) Members covered.—Paragraphs (1) and (2) apply to a member or former member of an armed force who first became a member of a uniformed service before August 1, 1986, and whose retired pay base is determined under section 1406 of this title.

(d) First COLA Adjustment for Members With Retired Pay Computed Using High-Three.—Notwithstanding subsection (b) but subject to subsection (f)(3), the retired pay of a member or former member of an armed force who first became a member of a uniformed service before August 1, 1986, or on or after August 1, 1986, if the member or former member did not elect to receive a bonus under section 322 (as in effect before January 28, 2008) or section 354 of title 37 and whose retired pay base is determined under section 1407 of this title shall be increased on the effective date of the first adjustment of retired pay under subsection (b) after the member or former member becomes entitled to retired pay by the percent (adjusted to the nearest one-tenth of 1 percent) equal to the difference between the percent by which—

(1) the price index for the base quarter of that year, exceeds

(2) the price index for the calendar quarter immediately before the calendar quarter during which the member became entitled to retired pay.

(e) Pro Rating of Initial Adjustment.—Notwithstanding subsection (b) but subject to subsection (f)(3), the retired pay of a member or former member of an armed force who first became a member of a uniformed service on or after August 1, 1986, and elected to receive a bonus under section 322 (as in effect before January 28, 2008) or section 354 of title 37 shall be increased on the effective date of the first adjustment of retired pay under subsection (b) after the member or former member becomes entitled to retired pay by the percent (adjusted to the nearest one-tenth of 1 percent) equal to the difference between—

(1) the percent by which—

(A) the price index for the base quarter of that year, exceeds

(B) the price index for the calendar quarter immediately before the calendar quarter during which the member became entitled to retired pay; and

(2) one-fourth of 1 percent for each calendar quarter from the quarter described in paragraph (1)(B) to the quarter described in paragraph (1)(A).

If in any case the percent described in paragraph (2) exceeds the percent determined under paragraph (1), such an increase shall not be made.

(f) Prevention of Pay Inversions.—

(1) Prevention of retired pay inversions for members with retired pay computed using final basic pay.—The monthly retired pay of a member or a former member of an armed force who first became a member of a uniformed service before September 8, 1980, and who initially became entitled to that pay on or after January 1, 1971, may not be less than the monthly retired pay to which he would be entitled if he had become entitled to retired pay at an earlier date based on the grade in which the member is retired, adjusted to reflect any applicable increases in such pay under this section. In computing the amount of retired pay to which such a member or former member would have been entitled on that earlier date, the computation shall be based on his grade, length of service, and the rate of basic pay applicable to him at that time, except that such computation may not be based on a rate of basic pay for a grade higher than the grade in which the member is retired. This subsection does not authorize any increase in the monthly retired pay to which a member was entitled for any period before October 7, 1975.

(2) Prevention of retired pay inversions for members with retired pay computed using high-three.—Subject to subsections (d) and (e), the monthly retired pay of a member or former member of an armed force who first became a member of a uniformed service on or after September 8, 1980, may not be less, on the date on which the member or former member initially becomes entitled to such pay, than the monthly retired pay to which the member or former member would be entitled on that date if the member or former member had become entitled to retired pay on an earlier date, adjusted to reflect any applicable increases in such pay under this section. However, in the case of a member or former member whose retired pay is computed subject to section 1407(f) of this title, paragraph (1) (rather than the preceding sentence) shall apply in the same manner as if the member or former member first became a member of a uniformed service before September 8, 1980, but only with respect to a calculation as of the date on which the member or former member first became entitled to retired pay.

(3) Prevention of cola inversions.—The percentage of the first adjustment under this section in the retired pay of any person, as determined under subsection (c)(1), (c)(2), (d), or (e), may not exceed the percentage increase in retired pay determined under subsection (b)(2) that is effective on the same date as the effective date of such first adjustment.

(g) Definitions.—In this section:

(1) The term “price index” means the Consumer Price Index (all items, United States city average) published by the Bureau of Labor Statistics.

(2) The term “base quarter” means the calendar quarter ending on September 30 of each year.

(3) The term “base index” means the price index for the base quarter for the most recent adjustment under subsection (b).

(4) The term “retired pay” includes retainer pay.

(h) Price Index for a Quarter.—For purposes of this section, the price index for a calendar quarter is the arithmetical mean of the price index for the three months comprising that quarter.