33 U.S.C. § 3045

(a) Officers first becoming members before September 8, 1980 Each officer on the retired list who first became a member of a uniformed service before September 8, 1980 , shall receive retired pay at the rate determined by multiplying— (1) the retired pay base determined under section 1406(g) of title 10 ; by (2) the retired pay multiplier determined under section 1409 of such title for the number of years of service that may be credited to the officer under section 1405 of such title as if the officer’s service were service as a member of the Armed Forces. The retired pay so computed may not exceed 75 percent of the retired pay base. (b) Officers first becoming members on or after September 8, 1980 Each officer on the retired list who first became a member of a uniformed service on or after September 8, 1980 , shall receive retired pay at the rate determined by multiplying— (1) the retired pay base determined under section 1407 of title 10 ; by (2) the retired pay multiplier determined under section 1409 of such title for the number of years of service that may be credited to the officer under section 1405 of such title as if the officer’s service were service as a member of the Armed Forces. (c) Treatment of full and fractional parts of months in computing years of service (1) In general In computing the number of years of service of an officer for the purposes of subsection (a)— (A) each full month of service that is in addition to the number of full years of service creditable to the officer shall be credited as 1 ⁄ 12 of a year; and (B) any remaining fractional part of a month shall be disregarded. (2) Rounding Retired pay computed under this section, if not a multiple of $1, shall be rounded to the next lower multiple of $1.