3.—(1) The overall amount of extra pension is—
(a)£6,500 for any financial year ending before 1st April 2016; and
(b)for any financial year beginning on or after that date—
(i)an amount determined by the Treasury for that financial year; or
(ii)if the Treasury has not determined an amount for that financial year, the amount calculated under sub-paragraph (2).
(2) If the Treasury has not determined an amount under sub-paragraph (1)(b)(i) for any financial year, the overall amount for that financial year is the amount to which the annual rate of a pension of an amount equal to the overall amount for the previous financial year would have been increased under PIA 1971 if—
(a)that pension were eligible to be so increased; and
(b)the beginning date for that pension were the first day of the previous financial year.