Just to add some confusion into the fold, there are often 'determinations' made and issued by the ATO with respect to schemes of arrangement and the like that cover the tax consequences for shareholders.
To draw on one example - a familiar one in my instance - Bellamy's was acquired give or take 18 months ago, and in that instance, the ATO declared
"CGT event A1" - effectively happened on the scheme implementation date, which was also the date shareholders were paid. The record date in that instance was a week prior.
Situations can vary from one to the next, but if the above is any sort of precedent - and I do believe I had a similar experience with another company, Vitaco, long before that - it may well turn out to be the implementation date as the relevant date.
You can read the relevant sections of the Bellamy's example
here, referring to parts (16) and (40).
