Global Tax 50 2015: Mike Williams

Mike Williams is a new entry this year

Mike Williams is a tax veteran who plays an important role in guiding the UK's international tax policy, but he will have jumped onto even more people's radars when he was appointed as the chairman of the BEPS Action 15 working group for the development of a multilateral instrument.

The ad hoc working group – which was created on May 27 2015, before the final BEPS deliverables were released – will be responsible for drafting the multilateral instrument for implementing BEPS around the world. This will essentially involve putting together treaty amendment rules to facilitate countries in implementing treaty-related BEPS recommendations.

Williams' three vice-chairs in the group are Mohammed Amine Baina of Morocco, China's Liao Tizhong and Kim Jacinto-Henares of the Philippines, all of whom feature in this year's Global Tax 50 list. While each of these figures performed influential roles outside of their Action 15 work over the past year, this showing is testament to the importance of the ad hoc group's work.

The working group has been signed up to by more than 90 countries. The agreement by OECD countries to sign up to a multilateral instrument to modify tax treaties was one of the pivotal aspects of the BEPS Project, and the group will now work to create the instrument capable of modifying the world's 3,500+ bilateral tax treaties.

Williams will need to show strong leadership; the working group has a tough timetable to adhere to, with negotiations on the instrument scheduled to be finished by the end of 2016.