Calls for a comprehensive income security policy are common in South Africa, frequently in the form of a basic income grant. These arguments tend to draw on two broad sets of literature that, although arguing to the same ends, are not usually combined or interrelated. First, there are analyses setting out the social and economic benefits of such a policy, focusing particularly on arguments of economic efficiency and affordability. Second, there has been much theoretical and normative work arguing (particularly) in favour of a basic income grant or other form of citizen's income. In this paper we aim to connect these literatures and to identify the most appropriate theoretical and normative justification for a comprehensive income security 'safety net' for South Africa.