Since 2014, directives in the area of direct taxation may include an obligation to tax income. This article examines the question of which obligation should prevail in the event of a conflict between a directive’s obligation to tax and a tax treaty obligation not to tax. This question of precedence is considered from three different perspectives: the international law perspective, the national law perspective and the European law perspective. This article concludes that the international law perspective, taking into account the national law and European law perspectives, appears to be, essentially, decisive (except for those EU Member States that can override, as a matter of national law, tax treaties). Based on this conclusion, it is recommended that tax treaties that (may) conflict with directives be renegotiated. The purpose of such renegotiations could be to include a subordination clause pursuant to which the tax treaty does not apply insofar as its application is incompatible with a particular directive or Union law obligations in general.