The trading is done out of a company that has other businesses involved. Why only 75% brokerage GST , its usually only $2.72 GST per transaction so hardly worth any grief.
China Gold: I declared the company as a trader from the start to avoid any issues. I find it simpler to record purchases /sales and SOH values instead of every transaction and top ups and sales , althought this can be done fairly easily in a company by treating the purchase of each compnay as a stock item and adding topups at new prices, these will average themselves and then sales to give a profit/loss on each company. I found the accountancy work (costs) in recording for CGT purposes when you are doing a number of transactions a bit heavy.
