More than twenty years ago, Michael Lang provocatively questioned the normative quality, and particularly the constitutional foundations, of the ability-to-pay principle in the area of direct tax law. While his arguments had and still have a significant impact on the academic debate, constitutional courts in Austria and Germany are still struggling with the normative classification of this principle. Similar questions and problems arise regarding the principle of neutrality in EU VAT law, which plays a fundamental role in the jurisprudence of the CJEU. In this article, Karoline Spies draws parallels between these two principles and - following the line of argument of Michael Lang - questions the necessity and relevance of the neutrality principle in EU VAT law.