The total cost base doesn't change. If you paid $1000 for your TAW shares, then you still paid $1000 for your AMAL shares.
The cost base per share will change. You'll need to take the money you spent on TAW (minus an amount for Cowan) and divide by the number of AMAL shares you now have.
Can't do the numbers completely, as I don't think we've been given an update about the class ruling for the demerger, have we? The last comment I can see on it was this announcement: https://www.asx.com.au/asxpdf/20180718/pdf/43wlzy79cwf3cd.pdf
Anyone have any ideas there?
TAW Price at posting:
30.0¢ Sentiment: Hold Disclosure: Held