In other words, Application of taxes are deferred until you withdraw the cash from these accounts.
If you have USD 2000 in your account
You invested it and earned USD 200 profit.
If 10% is the Tax rate.
While crediting the account for the USD 200, a tax of 10% would be not be deducted.
And, complete USD 200 would be credited in your account
However, at any point if you decide to withdraw USD 2100, which is nothing but 2000 main balance and surplus USD 100 earnt through profit.
A tax of 10% would not be applied on USD 100 which is – USD 10.