However, it will still be available for the capital gain on an asset that accrues up to that date.

This will apply where you have acquired an asset before that date and sell it after that date (or where it is otherwise liable for CGT after that date).

In these circumstances you will need to obtain a market value of the asset as of 30 June 2027 in order to get the benefit of the 50% discount on any gain accrued up to that time (unless you choose to use the proposed alternative apportionment method).