The only reason to open a separate account is if you require the discipline. If you are the type to spend money as soon as it enters your account, then a separate account is a good idea, despite the extra charges and admin hassles. The last thing you want to do is be late on SARS payments. They penalise you like crazy and its a very unfair fight.

If however you are more careful with your spending and your books are kept current so you know what you owe at the end of the month and make provision for it, then I see no need to go to the extra effort of opening a seperate account just for SARS.