This book introduces a practical methodology for the measurement of tax transaction costs (TTCs) in small and medium enterprises. TTCs comprise the administrative costs incurred by Governments to collect taxes, as well as the costs incurred by taxpayers to comply with tax laws. Measuring TTCs is critical to assess reducible costs, as well as to monitor progress towards their actual reduction. This publication analyzes also the results of the pilot testing of such methodology in two countries in Latin America (namely, Costa Rica and Uruguay).