The last decade entrepreneurship is on rise. Consequently academic researchers as well as society in general show an increased interest in self-employment. Interestingly, while examining the determinants of self-employment, it is argued that individuals choose entrepreneurship as their career path in order to avoid tax. Moreover, entrepreneurs have arguably greater scope compared to wage earners to under-report their incomes. Hence, in this context it is reasonable to think about the magnitude of self-employed income under-reporting. To measure latter, current book uses data drawn from the Household, Income and Labour Dynamics in Australia Survey (HILDA) for the years 2001 and 2003-2005. A method applied is an expenditure based approach developed by Pissarides and Weber (1989). A key idea is that under-reporting of incomes among entrepreneurs would be detectable in the data by using food expenditure equations. The investigation of self-employment income under-reporting is valuable and may illume policy makers about the undergound activities. Furthermore, the evidence that income concealing is likely to depend on the legal form of self-employment is of potential policy relevancy.