The book deals with VAT - Value Added Tax. Without claiming to characterise the entire structure of the tax, we focus on the adoption of this tax in the EU and national contexts, making an incursion into the evolution of VAT in Portugal. We pay special attention to the changes that have taken place in terms of exemptions and the incidence of reduced rates, in order to assess their implications for fiscal policy. Since taxes are the main source of funding for the Portuguese state and for most countries, we take this opportunity to question whether the aims of the current imposition of a tax such as VAT could be to shape the behaviour of taxpayers, thereby influencing the tax policy drawn up by government officials. Having analysed the structure of the tax, namely its system of rates and exemptions, the arguments and merits associated with such a structure, we conclude that the decision is above all political and greatly influenced by economic science. This book is aimed at all professionals specialising in the areas of law, taxation and economics, but also at academics, especially in these areas.