Scholars have debated the appropriate taxation of returns to debt – in the national and international arenas – at great length. Less explored is the normative foundations on which nation-states share the returns to share investment. A cosmopolitan view of the world demands that countries take seriously the project of justly allocating tax revenue associated with returns to share capital. In this paper, I explore common international practices that apply to the taxation of returns on shares in the cross border context, consider the historical evolution of the taxation of cross-border returns, and argue that, as a normative matter, a cosmopolitan view of the world demands a partnership between nation states be forged to appropriately allocate the taxation rights on those returns.