The authors* – Gabriel J. Felbermayr (LMU, Ifo Institute), Clemens Fuest (LMU, Ifo Institute), Hans Gersbach (ETH Zurich and chairman of the Board of Academic Advisors to the German BMWi), Albrecht O. Ritschl (LSE), Marcel Thum (TU Dresden, Ifo Institute, and chairman of the Advisory Board to the German BMF) and Martin T. Braml (Ifo Institute) –suggest a minimum three-month extension will be necessary to establish a European Customs Association.