Why doesn't the investment cost base reduce by the negative AMIT amount?
The fund is deemed segregated in full pension phase for the whole financial year.
If the fund is deemed segregated in full pension mode for the whole financial year, the tax cost base adjustment is not applicable, i.e. AMIT or tax-deferred, as there will be no taxable gain/loss.
If the fund is unsegregated during the year, then the tax cost base would be increased or reduced by the AMIT adjustments.