In this paper an overview is made of the determinants of voluntary tax compliance. Unlike previous treatments of this subject, the cost of taxpayer compliance is considered as an important determinant of overall level of voluntary compliance in a country. A number of ways that tax authorities reduce compliance are discussed, and the most common uses of information technology in providing taxpayer service is described. Finally, the paper considers some of the ways that such activities might be monitored so that only cost-effective measures are implemented.