Aussie, I believe the ATO will pro rata the profit. For instance, buy 100k on 2.1.07 and 50k on 1.3.07. Sell 75k on 30.1.08. ATO will deem that 2/3rds of the 75k is subject to the 12 month rule because 2/3rds of your total holding (150k) was 12 months old. You can't deem that the 75k was from the first purchase.
cosmos