A case comment dealing with the UK Supreme Court's decision in Fowler v Revenue and Customs Commissioners [2020] UKSC 22. The case concerns the effect on an income tax treaty of a domestic law provision deeming certain employed divers working in the UK to be treated for tax purposes as carrying on a trade. The central issue before the Supreme Court was whether the tax treaty provisions dealing with employment income or business profits applied. The comment deals with key reasons relied on by the Supreme Court in its decision that the deeming provision had no effect on interpretation and application of the tax treaty. Aspects considered include the relevance of Commentaries on the OECD Model Tax Convention, perceived double non-taxation, purposive interpretation, the relation between domestic law and income tax treaties as well as the effect of the court's decision on the collection of tax.