Dr O.C.R. Marres (1971) has been appointed Professor of Integrity of the Tax Base at the Faculty of Law of the University of Amsterdam (UvA).

Otto Marres focuses his research on, among other things, the erosion of the tax base. Tax revenues are under pressure due to tax avoidance and tax competition. States try to protect their base by means of anti-abuse provisions, and simultaneously seek to create a favorable investment climate. By achieving both goals international and EU legal standards should be met. The research by Marres is embedded in the research of the Amsterdam Centre for Tax Law at the University of Amsterdam, one of the centres of excellence of the Faculty of Law. The purpose of this research programme is to determine tax sovereignty boundaries. In addition, research is conducted into whether those boundaries should be made ​​wider or narrower according to several criteria, including tax base integrity.

Marres has been a tax adviser at KPMG Meijburg & Co since 2009. Before that he worked as a legal assistant at the Supreme Court of the Netherlands and as a lawyer at Stibbe and Linklaters LLP. In addition to these positions, Marres was an assistant professor at the University of Amsterdam. He has served as deputy justice at the The Hague Court of Appeal since October 2009. Marres has published numerous books, such as 'Base erosion by interest deduction' (Winstdrainage door renteaftrek, Kluwer, 2005 en 2008) and 'Dividend tax' (Dividendbelasting, Kluwer, 2006 en 2011), as well as articles, annotations and other publications. He is also an editor/writer for several tax law publications.