Undertakings for the Collective Investment of Transferable Securities (UCITS) involve collective investment funds, which are authorized to market their units among countries within the European Union. The objective of the original UCITS directive was to allow for open-ended funds investing in transferable securities to be subject to the same regulation in every Member State. It was hoped that once such legislative uniformity was established throughout Europe, funds authorized in one Member State could be sold to the public in each Member State without further authorization, thereby furthering the EU's goal of a single market for financial services in Europe. Unfortunately, the reality differed somewhat from the expectation. This insightful work examines the taxation of UCITS in Austria, Germany, the Netherlands, and the United Kingdom. It analyzes the tax consequences of the cross-border trade in units of UCITS for unitholders residing in the countries examined. It also features recommendations to remove the tax advantages and disadvantages that occur in cross-border trading.