This book explores the impacts of tax policies in various economies around the world. It looks into both the effects on resource allocation (efficiency) and on the distribution of income and welfare. As such, this book deals with the classical model of public finance literature which has been in continuous discussion for over 200 years. The main distinction which sets this book apart from earlier literature is its emphasis on quantification using numerical simulation methods. This book brings together a number of papers which the author has published (some jointly) on the computation of general equilibrium in the practice of taxes. The aim of the book is to make these works accessible to both researchers and policy practitioners interested in results of national simulations and their policy implications. It sets out to analyze taxation systems in detail using both theoretical knowledge and applied methodology.