This book was presented to Professor Dr Rainer Prokisch on his retirement from the chair in International Tax Law at Maastricht University. He arrived at Maastricht in 2000 and was twice the Head of the Department of Tax Law for over ten years. With Rainer Prokisch leaving, we look back on a period during which the Department of Tax Law launched its successful LL.M Programme in International & European Tax Law and became far more international. When Rainer Prokisch entered the department, he was the first foreigner in any academic position. Still, in the 22 years that followed, we have been joined by colleagues from Argentina, Brazil, Chile, Colombia, Estonia, Germany, Italy, India, Poland, Portugal, Romania and Spain. We thank Professor Prokisch for contributing to these team efforts that shaped our department’s international and European ambitions. The editors have brought together a pretty varied liber amicorum, as the contributions included in this book will show. In line with the Maastricht tradition, authors have been given a choice to write their contribution either in English or Dutch, whatever suited their topic best.