BEPS principal purpose test and customary international law

The overall aim of this article is to analyse the principal purpose test as an emerging rule of customary international tax law. By means of the principal purpose test, the tax administration can deny the tax treaty benefit if one of the principal purposes of the action undertaken by the taxpayer was to obtain a benefit. This principal purpose test has been developed by the OECD with the political support of the G20 as one of the actions to tackle Base Erosion and Profit Shifting by multinationals (BEPS Project). At the time of writing, 137 jurisdictions including non-OECD, non-G-20 countries have committed to the implementation of the principal purpose test in their current and future tax treaties. Based on the analysis of the objective element (state practice) and subjective element (accepted as law), there are indications that this principal purpose test can emerge as a principle of customary international law. In the past, international tax law scholars addressed the customary international law regarding the OECD/UN tax treaty Models, the OECD Harmful Tax Practices, and the arm’s length principle. However, current international tax developments, including the BEPS Project, call for an analysis of the main elements of customary international law in respect of the principal purpose test, a general anti-avoidance rule that by its own nature, is often general, vague, and imprecise. Therefore, the findings of this article can be useful for generating new areas of research by international public law, international law, and international tax law experts