Tax avoidance, often defined as tax reduction strategies that fall within the letter of the law but violate its spirit, has given rise to contentious public and academic debates about the legal and ethical responsibilities of taxpayers and their advisors. If a tax arrangement is legal (or more precise, the law entails the tax advantages sought), can it then still be unethical? And to what extent does it matter if one is a taxpayer or acts in an advisory capacity? In this talk Laurens van Apeldoorn aims to clear up some conceptual problems and confusions – regarding the definition of tax avoidance, the character of the relevant legal and ethical norms, the relationship between law and morality, the complicating function of juridical anti-avoidance rules, and the role-specific responsibilities of members of a profession – to propose new answers to these  questions.