But here's another aspect of income tax that some people don't think of. We are told that when you buy a litre of petrol, around about $1.40 of that is excise tax and GST and emissions trading scheme levies and a couple of other minor levies that are put on to a litre of petrol; they add up to $1.40. But what they don't tell you is that if you do a full economic analysis of what people are paying in terms of total tax to buy a litre of petrol, you'll also have to go out and earn the money, and when you do that, you pay income tax.