The issue of subsidy control was one of the major points of contention during Brexit negotiations. The United Kingdom (UK) adopted a minimalist approach, seeking to align its post-Brexit framework with WTO rules. The European Union (EU), instead, insisted on preserving the level playing field through the continued application of its State aid regime to the UK. The article argues that, given the high degree of economic interdependence between the two economies, a system based on WTO subsidy disciplines would not have been sufficient to safeguard the level playing field between the EU and the UK. Thus, the article maintains that the EU–UK Trade and Cooperation Agreement (TCA) is unprecedented in the landscape of international trade agreements, as a consequence of the rationale underpinning it. It also contends that this rationale has shaped all the substantive and procedural elements of its subsidy control regime.