It is a bit complicated to detail the investment/trading plan....

It is a bit complicated to detail the investment/trading plan. However to briefly describe the process it is a case of having trading accounts and seperate investment accounts. Also as a retired aged couple there are other complications and advantages. Also there are trust funds involved. All legal and above board.

To sell shares worth a million dollars does not mean there is a million dollars taxable profit. It is the profit that is taxable not the total amount. Then there is the tax free threshold (by two for a couple). Then the sale can be made over more than one financial year which further reduces the overall tax.

The taxation laws are complicated and correct advice is necessary. There are plenty of accountants that can't handle it and there are others that try and outsmart the tax man which usually ends in trouble. I recommend asking the tax office for a ruling on the tax implications of any trading plan. Get the information in writing as it applies to your individual case. Then you know the cost of the tax and can make provision for it.