If you purchased shares in the Commonwealth Bank of Australia (CBA) and Telstra share sales and you paid for them in 2 instalments, you would have received an 'instalment receipt' after making your first payment. The instalment receipts were issued as evidence that you owned a beneficial interest in the shares.
If you sold the instalment receipts or shares for more than the amount you paid for them, you may have to pay capital gains tax on the difference between the cost base of the instalment receipts or shares and the capital proceeds from the sale. The cost base includes indexation if you disposed of your shares or instalment receipts 12 months or more after acquiring them.
Indexation of the first instalment amount is available from the date on which you were allocated the shares. The CBA share allocation occurred on 13 July 1996 and the Telstra allocation on 15 November 1997. The final instalment is taken to have been paid and indexation applies from the date the relevant trustee received the payment on behalf of the Commonwealth as vendor.
For the CBA share sale, the trustee received the payment on or around 14 November 1997 or the earlier date on which they received a discounted sum in satisfaction of a final instalment.
For the Telstra share sale, the trustee received the payment and the transfer of the sale shares occurred on or around 17 November 1998.
For more information, see Taxation Determination TD 98/11: CBA and Telstra public share offers or the publication Personal investors guide to capital gains tax.