Estimating the timeline of the Brexit negotiations

Published 21/05/2018   |   Last Updated 27/05/2021   |   Reading Time minutes

In April 2017, the Research Service published its first Brexit timeline which aimed to set out how the key events in negotiations on the UK’s exit from the EU. Along with domestic preparations for the UK’s withdrawal and how key constitutional events in the Assembly and Wales may interlink over the next 24 months. In publishing that first timeline we committed to update and develop the timeline as the negotiations progressed.

Below is the third iteration of the timeline. We published the second iteration in September 2017. The timeline is based on the best public information available at this time and is likely to be subject to further refinements and amendments as negotiations progress over the coming weeks and months.

Image of Brexit timeline

What do the different iterations show?

Looking back over the three iterations, one of the most identifiable changes is that the UK’s own internal preparations for withdrawing have taken longer than originally anticipated. For example in the first timeline we produced we estimated that the EU (Withdrawal) Bill would have received Royal Assent by March 2018. We now estimate that the Bill will receive Royal Assent in July 2018.

The other noticeable change is that the First Minister for Scotland, had in April 2017, stated that the Scottish Government would hold a second referendum on independence before the UK left the EU in March 2019. The First Minister for Scotland subsequently announced that a date for a referendum would not be set immediately but that she will reconsider the need for a referendum in the autumn of 2018.

Lastly, in accordance with the UK Government’s proposed timeline the first iteration estimated that the UK would have reached an agreement with the EU both on the terms of its withdrawal and the detail of the future trading relationship. We now know that whilst the UK and EU hope to reach an agreement on a political declaration on a framework for a future relationship by March 2019 they are unlikely to have agreed on the details of trade and other future agreements. Instead if they can reach an agreement on the withdrawal issues there will be an additional transition period of 21 months to reach agreement on the detail.


Article by Nia Moss & Helen Jones, National Assembly for Wales Research Service