Werner Haslehner is ATOZ Chair for European and Intemational Tax Law at the University of Luxembourg, Luxembourg, Georg Koffer is Professor of International Tax Law in the Institute for Austrian and International Tax Law at Vienna University of Economics and Business, Austria, Katerina Pantaratou is Associate Professor of Tax Law at the University of Luxembourg, Luxembourg and Alexander Rust is Professor of Tax Law in the Institute for Austrian and International Tax Law at Vienna University of Economics and Business, Austria.