(1) The indexation factor for a financial year is the number worked out by:
(a) ascertaining the index number for the most recent quarter for which the Australian Statistician has published an index number, as at the start of the day on which the Treasurer makes the first determination under subsection 7(1) of an amount in relation to the financial year; and
(b) dividing that index number by the index number for the quarter 12 months before the quarter mentioned in paragraph ( a); and
(c) adding 0.030 to the number worked out under paragraph ( b).
(2) The indexation factor is to be calculated to 3 decimal places, but increased by .001 if the 4th decimal place is more than 4.
(3) Calculations under subsection ( 1) :
(a) are to be made using only the index numbers published in terms of the most recently published index reference period for the Consumer Price Index; and
(b) are to be made disregarding index numbers that are published in substitution for previously published index numbers (except where the substituted numbers are published to take account of changes in the index reference period ).