Nation states in the Asia Pacific need to increase tax revenues but face many challenges. This article discusses the challenge of taxation in an age of capital mobility and tax competition. It then considers two opportunities that have recently been championed by the G20, which could enable governments to strengthen national tax systems by international cooperation. The first opportunity is the establishment of transnational tax administrative cooperation. The second opportunity is the potential for countries to develop a new multilateral framework for sharing the international capital tax base, which may arise under auspices of the Organisation for Economic Co-operation and Development Base Erosion and Profit Shifting project. As Chair of the G20 in 2014, Australia has a key leadership role to play in supporting countries in the region to grasp these opportunities.