The Mauritius Convention on Transparency and the Multilateral Tax Instrument: models for the modification of treaties?

The investment treaty network and the tax treaty network comprise more than 3,000 treaties each. The provisions of these treaties generally are highly customized on the basis of the investment flows and economic interests of the contracting States. The number of treaties in force and their customization potentially turn the amendment of these treaty networks in their entirety into a cumbersome and long process. To modify the treaty networks in a swift and coordinated manner, the investment treaty makers and the tax treaty makers almost contemporaneously developed the idea of implementing treaty changes through a single multilateral convention. On 10 December 2014, the United Nations adopted the Convention on Transparency in Treaty-based Investor–State Arbitration, also known as the Mauritius Convention. In addition, on 24 November 2016, the Multilateral Convention to Implement Tax Treaty Related Measures to Prevent Base Erosion and Profit Shifting (BEPS), commonly referred to as the Multilateral Tax Instrument, was concluded under the aegis of the Organisation for Economic Co-operation and Development (OECD). The Mauritius Convention and the Multilateral Tax Instrument share the object and purpose of modifying an extensive number of treaties. However, due to their novelty, little research has been done until now on their common characteristics and differences. The article aims at filling this gap by comparing both multilateral conventions. It also aims at drawing lessons from the analysis of both multilateral conventions that might be of benefit for future modifications of an extensive number of treaties through a single instrument.