The Institute for Government has summarised the current four broad models for conducting financial services trade between the UK and the EU as follows:

• Passporting:
  Firms based in EU member states, and non-EU states that are members of the European Economic Area (EEA), can sell their services freely within the bloc under a system known as ‘passporting’.
• World Trade Organization (WTO) terms:
  States outside the EEA, or ‘third countries’, typically do business with Europe on the terms outlined in the WTO’s General Agreement on Trade in Services (GATS).
• Equivalence:
  Some third countries receive preferable market access rights regarding certain services, on the basis that their laws and supervisory frameworks are deemed ‘equivalent’ to the EU’s by the European Commission and a committee of experts from member states.
• Free trade agreement (FTA):
  Other third countries have attempted to cover financial services as part of a broader FTA with the EU. The Comprehensive Economic and Trade Agreement (CETA) between the EU and Canada is the most recent example of this.