Taxpayer behaviour has in South Africa moved to the forefront of the investigation of revenue collection with regular tax awareness campaigns being launched by the South African Revenue Service (SARS). Issues relating to tax amnesty and the contribution of the informal sector (second economy) to tax revenue have become important. This paper attempts to find explanations, be they economic or psychological, for taxpayer behaviour in South Africa. Factors influencing tax evasion and ultimately collection targets are thus examined. A questionnaire was designed to determine how individuals, in this case a sample of students, respond when filing taxes. Each question frames a scenario to invoke a specific tax regime. The paper’s unique findings show, generally, that behaviour is to a large extent determined by economic factors, specifically inequality as predicted by the expected utility theory. This theory also successfully predicts 50 per cent of the responses to the control questions. The remaining 50 per cent are explained by combined economic and psychological factors, modelled by the prospect theory. This is significant considering the fact that the results were generated within a developing and not a developed context as is the case in most studies of this type.