When the Transition Period ended on 31 December 2020, the UK left the EU Customs Union and Single Market. Just ahead of the end of the Transition Period, the UK and the EU agreed the terms of a bilateral free trade agreement contained in the Trade and Cooperation Agreement (TCA).
A bilateral free trade agreement allows two parties to trade on preferential terms, but only if the goods satisfy the rules of origin agreed between the parties. These rules are contained in the TCA and are summarised below.
Source Moore and Smalley