In calculating capital gains or losses for tax purposes, we use the first-in-first-out (FIFO) method to track the cost by default.
Suppose you bought 100 A-shares at AU$600 on September 5, 2022, and another 100 A-shares at AU$800 on September 10, 2022; then you sold 100 A-shares for AU$1,000 on September 15, 2022. Under FIFO, what you sold are those 100 A-shares you bought on September 5, 2022, and your cost is AU$600. Thus, your capital gain is AU$1,000 - AU$600 = AU$400.
If you wish to use other methods to determine your cost, please consult a qualified accountant or tax advisor.
Neither Futu Securities (Australia) Ltd nor its affiliates give tax advice. Please consult a qualified tax advisor about your financial planning and tax issues.