1Determining the residence of a taxpayer is one of the most important aspects of modern tax systems. For an individual taxpayer who migrates, a common trend in the modern world, the questions are where the person is ordinarily resident and whether the place of ordinary residence can change. The two key cases in South African jurisprudence that are cited whenever the question of residence or ordinary residence is raised are Cohen v CIR and CIR v Kuttel. These cases form the foundation of this article as they examine the meaning of “resident” and “ordinary” resident” in the modern milieu. The article provides the historical background to these two seminal cases, extracts the key principles handed down in each of the judgments and evaluates these principles against definitions of “resident” used in other countries with a view to evaluating whether the definition of “resident” for South African tax purposes, premised on the fundamental principles from these two historic cases, is still relevant and appropriate. The article queries whether the concept of “ordinary resident”, with its connotation of permanence, should be updated to reflect the modern reality of transience and mobility. The conclusion reached is that the existing definition of “resident” may be in need of updating to accommodate global trends and to bring the South African tax legislation more in line with modern developments and the introduction of an objective test could provide more certainty to both taxpayers and the fiscus, but this benefit should be weighed against the possible cost of a loss to the tax base.