For a discussion on formulary apportionment and the extractives industry, read Kerrie Sadiq’s latest article in the Journal on Financing for Development. This article builds on the work of Picciotto and others who have previously highlighted the tensions around a formulary apportionment regime for the extractives industry and, in doing so, focuses on source jurisdiction entitlement concerns in the Global South. It addresses the questions outlined above and considers the arguments for and against a fourth factor or allocation key, such as a production volume factor or a source-based sales factor that modifies any general apportionment formula and reduces the significant emphasis on sales at the destination and the role of separate charges. The article ultimately suggests that while economic rents should be taxed separately outside the corporate income tax regime, reform of the corporate income tax system based on unitary taxation and formulary apportionment that addresses the fundamental flaws in the current regime should be undertaken. However, the article also recognises that this top-down approach is one that is difficult to attain and that a pragmatic bottom-up approach, which is being witnessed in the current international tax reform arena, may also benefit resource-rich countries, especially those in the Global South.