This article is a legal analysis of jurisdictional corporate tax competition under the objectives of EU law. It compares the legal foundations for tax competition, on the one hand, and tax harmonisation on the other. This derives from three constituent analyses: the first section of this article conducts an economic examination of tax competition against the criteria of EU tax policy. It finds that tax base and rate competition is demonstrably accordant with the economic objectives of EU law. This implies two correlating hypotheses pursued in the following sections. The second analysis of this article investigates and confirms that tax competition is protected by the CJEU under the principles of negative integration. The third analysis investigates and confirms, by reference to the proposed Common Corporate Consolidated Tax Base, that tax harmonisation is inherently unlikely to adhere to the objectives of EU law and therefore the criteria for positive integration. The paper concludes that tax competition is in economic imperative protected in EU law under the objectives of the Treaty.