In March 2018, the European Council adopted its guidelines for negotiating the future relationship and confirmed the April 2017 offer of a free trade agreement with zero tariffs and zero quotas on the condition of agreeing common standards on fair competition. EU leaders added that the UK had to respect the December 2017 agreement that Northern Ireland would align with EU rules in the absence of any other workable solution. Brexiters later criticized Theresa May for rejecting Donald Tusk's offer of a free trade area but omitted to mention it came with strings attached on Northern Ireland and a level playing field, which were not hidden in the fine print but part of the documents that EU leaders published.

Barnier's relationship models

Juncker and Barnier kicked off a discussion on the future relationship three months before, at the December 2017 European Council meeting, when EU leaders refrained from opening a conversation with the UK on the future, partly because of its immediate backtracking on the withdrawal agreement in political discourse. Macron and other leaders insisted on kicking off an internal EU discussion on what lied ahead. Barnier presented a slide that visualized the various models of third-country relationships the EU had already agreed (see Figure 6.1). The UK's red lines of not wanting any compromise on sovereign control of its laws, money and borders had it depicted as tumbling down a flight of stairs. EU membership was shown as the best relationship with the EU and marked at the top of the stairs. The second-best model was shown as Norway. Its membership of the single market facilitates trade and doing business across the Norwegian–EU border but obliges Norway to follow EU rules and jurisprudence. Norway pays for EU cohesion policy that accompanies the economic freedoms of the single market and accepts free movement of people. Such closeness to the EU, however, was not compatible with the UK's preferences.

Switzerland was placed one step lower than Norway. Just as Norway, Switzerland is in the Schengen area and respects free movement of EU nationals but the Commission and EU member states regarded Switzerland as an anomaly. It participates in the single market for some economic sectors, such as aviation, but not others, such as financial services.