Valid point Dave. Unfortunately getting the data I'm looking for is not simple.

Currently the SARS budget is around 1 trillion. GDP is around 4 trillion.

However some initial layman's investigation seems to indicate that GDP is an inadequate measure. It seems to only feature net exports which means the total for exports plus imports would be much higher. It also seems to only calculate the value of final products produced, but there could be many exchanges before the product gets to that stage. Of course I could have this wrong. How much higher is the nation's internal cash flow than GDP - not sure.

I tried the sales of the top 100 JSE companies and came up just short of the 4 trillion mark again. I excluded the big plc companies as I think most of their sales occurs out of SA. Again , not much meaning as I have no way of measuring what all the unlisted companies generate in terms of revenue. Government expenditure still has to be added, as well as personal revenue and expenditure.

Short answer is that its a bit of a guess, and unless someone knows the figure for all bank account activity its going to remain a guess.

I found this website which calls the type of tax TEAL http://ddforum.co.za/faqs. They reckon the rate will be closer to 1%.

On the other hand if its 10%, do most of the benefits still not remain?