The primary source of income for the RAF compensation scheme is a levy raised on fuel. The levy is measured in terms of cents per litre on petrol and diesel fuel sold in South Africa and forms part of the general fuel tax regulated by government. The fuel levy per litre is set by National Treasury on a yearly basis, whereas total fuel sales are influenced by a number of macro-economic factors. On an annual basis, the RAF requests National Treasury for an increase in the RAF Fuel Levy, based on a financial model and a calculation of its costs during the coming year. The full extent of the RAF Fuel Levy requested is seldom granted. This is because National Treasury has historically set the levy on the basis of a pay-as-you-go principle rather than with the purpose of establishing a fully funded position for the RAF. During the 2012 financial year the RAF Fuel Levy was set at 80 cents per litre.