All this talk of shortselling led me to check the rules.On the...

All this talk of shortselling led me to check the rules.
On the Sharesight site:

Avoiding wash sales. In 2008, the Australian Tax Office (ATO) issued issued tax ruling TR 2008/1, which specifically outlaws arrangements where “…in substance there is no significant change in the taxpayer’s economic exposure to, or interest in, the asset, or where that exposure or interest may be reinstated by the taxpayer”.In other words, the ATO prevents investors from selling a stock in one financial year to take advantage of a capital loss event, only to buy that stock again in the new financial year. This is known as a “wash sale” and the ATO will disallow the loss if the sole intention of the sale was to minimise tax. As Sharesight Executive Director Andrew Bird said, “if you are going to sell, make sure you really mean it. If you still believe in that stock then choose a different ‘loser’ to sell to offset your gain.""

So selling low for tax loss may mean you miss out on a big rise next year.