(a)(1) Subject to paragraph (2), effective at the beginning of the first applicable pay period commencing on or after the first day of the month in which an adjustment takes effect under section 5303 of title 5 in the rates of pay under the General Schedule (except as provided in subsection (b)), each salary rate which is subject to adjustment under this section shall be adjusted by an amount, rounded to the nearest multiple of $100 (or if midway between multiples of $100, to the next higher multiple of $100) equal to the percentage of such salary rate which corresponds to the most recent percentage change in the ECI (relative to the date described in the next sentence), as determined under section 704(a)(1) of the Ethics Reform Act of 1989. The appropriate date under this sentence is the first day of the fiscal year in which such adjustment in the rates of pay under the General Schedule takes effect.

(2) In no event shall the percentage adjustment taking effect under paragraph (1) in any calendar year (before rounding), in any salary rate, exceed the percentage adjustment taking effect in such calendar year under section 5303 of title 5 in the rates of pay under the General Schedule.

(b) Subsection (a) shall not apply to the extent it would reduce the salary of any individual whose compensation may not, under section 1 of Article III of the Constitution of the United States, be diminished during such individual’s continuance in office.