A tax ruling is a written interpretation of the law issued by a tax administration to a taxpayer. It is in most cases binding for the tax administration that issues it. Tax rulings cover a broad set of written statements, many of which are uncontroversial. However, those rulings that are so-called ‘advance tax agreements’ with multinational corporations have become an issue of much debate. One such type of agreement are the so-called advance pricing agreements (APAs), which are used by multinational corporations to get approval of their transfer pricing methods. Advance pricing agreements and other advance tax agreements have become increasingly controversial after the LuxLeaks scandal, as well as several EU state aid cases, showing how such deals can be used by multinational corporations to avoid taxes on a large scale.