Many tax policies in Australia and comparable countries are based on a completely rational individual decision maker. However, recent evidence in the fields often referred to as behavioural insights (combining behavioural economics and psychology) have shown that people are neither completely rational not completely irrational. Rather, they exhibit predictable biases that reduce the probability of achieving their own stated aims. In this paper, we summarise the evidence on behavioural insights related to tax compliance, with a particular focus on the more limited set of research on the decision making of small-medium enterprises.