Whilst the free movement of goods, capital and labour across borders, and the freedom to establish a business abroad, are the neoliberal cornerstones of global economics, it is the nation state that continues to dominate global politics. One result of this disconnect between international trade and national power is the ability of persons to benefit from location-specific advantages while paying little or no tax in the host jurisdiction. Although there is a strong argument that states are under an obligation to protect their citizens from these tax-avoiding free-riders, the available solutions are seemingly sub-optimal. Unilateral solutions run the risk of causing double taxation, investor uncertainty and other obstacles to free trade, thus putting foreign investment and economic growth at risk. Multilateral solutions require inroads into state sovereignty, which not only has government revenue implications but also means state power being ceded to a global regime that lacks the bite of hard law. Thus, states find themselves in a quandary. Should they trade autonomy and legislative freedom for the promise of a global public good that ultimately lacks certainty with regards enforcement? Or should they risk their economy and use their power to compel global actors to pay a fair share of tax? This article argues that if liberty, guaranteed by certainty of legal outcome, is the moral justification of law, any erosion of sovereignty, temporary or otherwise, in favour of aglobal soft-law regime must guarantee sufficient certainty for taxpayers; and, if benefit theory is an acceptable moral justification for taxation, a global tax system that respects locational benefits would provide a fair share of tax revenues for states. Accordingly, there is a good argument that global formulary apportionment (for producers) and a destination-basis goods and services tax (for consumers) are the right direction of travel when it comes to international tax cooperation.