Asa client you receive a Contract Note and pay against that.
On the Brokers Account he has costs of purchases for the year from ASX and receipt of income from Clients. If the churn shows a profit it would show up in the difference in the revenue received from clients minus Brokers cost of ASX purchases. If positive, its Broker earnings from trading activity and Broker pays the tax.
Good ole commonsense, but I'm no accountant.
Sorry, but no cigar.
CDU Price at posting:
$3.23 Sentiment: Hold Disclosure: Held