This article argues that the taxing right of market jurisdictions under Pillar One is justified by commonly invoked and widely accepted principles in international taxation. This is not just a desirable outcome of the international coordination on the allocation of taxing rights but a moral demand that the inter-state allocation of taxing rights must comply with. A principle-based allocation of taxing rights is a precondition for the legitimacy and thus the equity of the international tax regime. Principles, such as ability to pay, the benefits principle and economic allegiance, provide a normative justification for asserting tax jurisdiction. Despite the criticism regarding their vagueness, indeterminateness, and overlaps between their meaning, the benefits principle and economic allegiance have a definite function in the international tax regime insofar as they designate the countries that have a legitimate claim to tax international income.