Taxation has been identified by businesses all over the world as one of the biggest constraints for doing business. The purpose of this handbook is to provide policy makers especially in developing countries with a framework to assess a tax system in its entirety, measure the burden imposed by the tax including the compliance cost of tax administration, and define best practices for tax policy and administration that will yield a tax system that is simple and predictable and does not create an undue burden on private enterprise. Topics addressed in this handbook include Measuring Tax burden, Political Economy of Tax Simplification, Tax Policy Simplification, Tax Administration Simplification, Tax Incentives, Sub-National Tax Simplification, Corruption and Tax Simplification and Taxpayer Education and Assistance.