29 July 2021 Yohannes Ayele is Research Fellow in the Economics of Brexit at the University of Sussex and Fellow of the UKTPO. Since 1 January 2021, the UK’s trading relationship with its biggest and closest trading partner—the EU—has been governed by the Trade and Cooperation Agreement (TCA). Under the TCA, UK exports to the EU face zero-tariff and zero-quota. However, to claim zero tariffs, exporters must meet the rules of origin requirements and be able to provide proof of origin. Where exporters do not meet the requirements they end up paying the tariff. Even those exporters that can meet the rules of origin requirement, because of the cost of the paperwork and requirements for proof of origin needed to claim the zero tariff, they may instead choose to pay the tariff. The latter is more likely where the tariff preference margin (i.e., the difference between MFN non-zero tariff and the zero-tariff under TCA) is very low. These problems— the rules of origin requirements and costs associated to claim zero-tariff—could be particularly challenging for smaller companies. Therefore, in practice, firms may end up paying tariffs despite the zero-tariff and zero-quota deal under the TCA. […]