The arm's length principle and the notion of permanent establishment are the two pillars of international corporate tax. Drafted in 1920, they are now under the fire of acute criticism and they appear to have become obsolete: they are unable to face the challenges of a global and digital economy. This dissertation attempts to answer three research questions: What are the flaws of the arm's length principle? What are the alternatives? Should the arm's length principle be replaced? The examined corporate income tax systems are submitted to a two-part analysis. The first part is descriptive. It assesses how each system answers the three fundamental international tax questions: whom to tax, what to tax, and where to tax? The second part is critical. It examines these answers in light of three long-established principles: those of practicability, efficiency and fairness. As a conclusion, this dissertation proposes two orientations for international corporate taxation. First, it should rely on the source principle rather than the residence principle. Second, it should embrace the Common consolidated corporate tax base proposed by the EU, rather than the Pillar One proposed by the OECD.