There is a growing literature on the new politics of tax justice and the institutional and structural barriers to reforming the international tax regime to address corporate tax avoidance. This paper analyses the normative challenges for establishing a fairer and more sustainable international tax regime arguing that it will be necessary to establish and consolidate norms and associated standards to define what constitutes ‘fair’ taxation. The fact that corporate tax avoidance is legal allows firms engage in tax avoidance without compromising their moral authority and, as a result, tax advocates of tax justice have to promote the idea that that firms have legal and moral obligations when it comes to managing their tax affairs.