Brexit (2016 - 2020)

A timeline to understand Brexit.

(From Gilbert (2020), pp. 21-23 and Walker (2021), pp. 62-63 and p. 75)

May 22-25, 2014: European Parliament elections. In Great Britain, the United Kingdom Independence Party (UKIP) takes 27.6 percent of the vote, increasing pressure on Prime Minister David Cameron to negotiate a special deal forBritain.

February 19, 2016: The European Council negotiates a special deal with Great Britain that exempts Britain from involvement in political union and allows Britain to restrict the welfare benefits it pays to immigrants from other EU countries.

June 23, 2016: Britain votes to leave the EU by 52 percent to 48 percent; 17.4 million British citizens vote to leave. Prime Minister David Cameron resigns the following day.

March 29, 2017: Prime Minister Theresa May formally notifies the European Council of Britain's decision to leave the EU under article 50 of the Treaty of Lisbon. Britain has until March 29, 2019, to negotiate and ratify a treaty withdrawing from the EU.

November 14, 2018: Publication of the Withdrawal Agreement (WA) between the United Kingdom and the EU. It is subsequently approved by the European Council and provokes a challenge to May's leadership of the Conservative Party.

January 15, 2019: WA rejected by the House of Commons by 432 votes to 202. It is the largest defeat by a British government in parliamentary history. The WA is subsequently rejected on March 12 by the fourth largest margin in parliamentary history.

March 21, 2019: The European Council approves a British request for an extension to the article 50 procedures. Britain is given until May 22, 2019, provided that the House of Commons approves the Withdrawal Agreement. Otherwise, Britain must leave on April 12.

March 29, 2019: the WA is again rejected by the House of Commons.

April 10, 2019: Following a further British request for an extension, the European Council sets a new date of October 31,2019, for "Brexit."

May 23-26, 2019: European Parliament elections are won by the European People's Party. Right-wing populist and nationalist parties make gains, but so do pro-EU Greens and Liberals. In Britain, the Conservative Party is defeated by the newly formed "Brexit Party.'

October 17, 2019: The European Council approves a revised WA with the British government, which is now headed by Boris Johnson. The October 31 deadline for Britain to leave the EU is subsequently extended to January 31, 2020, and Britain holds a general election on December 12, 2019, in a bid to break the parliamentary deadlock. General Election results in Conservative Party majority. The Prime Minister pledges “to get Brexit done” by 31 January 2020.

19 December 2019: The British government publishes the European Union (Withdrawal Agreement) Bill.

23 January 2020: The European Union (Withdrawal Agreement) Act 2020 becomes law,

having received Royal Assent. This is the legislation that will implement the withdrawal

agreement negotiated by the UK and the EU.

31 January 2020: At 11pm the UK leaves the European Union and enters the transition

period.

1 February 2020: The transition period begins. 

15 June 2020: The Prime Minister meets EU leaders and asks them to “put a tiger in the tank” of stalled talks. 

30 June 2020: The deadline to request an extension to the transition period, currently due to conclude at the end of December, passes.

9 September 2020: The UK Internal Market Bill is introduced and receives criticism from EU leaders. 

16 September 2020: The European Commission President warns the UK Government against reneging on the Brexit deal. 

29 September 2020: The UK Internal Market Bill passes its Third Reading in the House of Commons and moves to the House of Lords. 

1 October 2020: The European Commission President announces the EU will initiate legal proceedings to prevent the UK from trying to use domestic legislation to override aspects of the Brexit Withdrawal Agreement.

17 December 2020: The UK Internal Market Bill receives Royal Assent and enters UK law. 24 December 2020: The Brexit deal (the EU-UK Trade and Cooperation Agreement (TCA)) is sealed. 

30 December 2020: Parliament is recalled to pass the European Union (Future Relationship) Bill. 

31 December 2020: The transition period ends at 11pm and the UK leaves the EU single market and customs union.

Implications for the European Union and the European institutions.

Brexit has had limited impacts on the European Union’s macroeconomic performances.

Both the International Monetary Fund^[1] and the European Commission^[2] respectively predicted 0.2% to 0.5% and 0.5% drops in the European Union’s aggregated GDP prior to the Trade and Cooperation Agreement (TCA) coming into effect. Such results were confirmed by later studies assessing the effects of the TCA^[3].

Moreover, Brexit was found to have had a positive effects of about 48% on EU intra-trade, while it had a negative effect of 15% on UK-EU trade - with no specific impact of the TCA^[4]. 

Brexit also has had impacts on European stock markets as it had increased volatility transmissions and financial integration across EU-15 trade markets^[5].

However, Brexit’s effect had differentiated effects across the European Union’s member countries. For example, Northern Ireland - to which the United Kingdom was a key trade partner - faced significant negative economic impacts of Brexit^[6]. The Withdrawal Agreement comprised a “binding protocol on Ireland and Northern Ireland” that allowed “Northern Ireland to remain in the UK customs territory and, at the same time, benefit from access to the Single Market for the movement of goods”. However, as Ireland still faced difficulties after Brexit, the Windsor Framework completed the TCA in 2023 - an agreement that was made possible as the “Protocol was designed to be amendable so that unforeseen challenges to its implementation can be addressed by EU-UK Joint Committees”^[7].

Other important trade partners of the UK, namely Belgium and the Netherlands^[8],[9] as well as Germany and France were impacted by Brexit^[10].

It is important to note that Brexit effects’ assessments are particularly complicated to produce as the long-run process of the United Kingdom’s departure of the European Union was, and is still, embedded in a “multitude of overlapping events”^[11] (Covid-19 being one of the major confounders), as well as the “heterogeneity of political responses and market attention across time”^[12].

How Brexit set a precedent for European institutions to adapt to opt-outs of member countries.

If the consequences of Brexit on the European Union’s macroeconomic performances have not been drastic nor significantly impeding, the United Kingdom’s opt-out of the European Union, being the first case of departure from the European Union, was a major challenge for the European institutions. We thus decided to include Brexit in the crises timeline as it has brought European institutions to produce unprecedented types of formalized process and agreements with a leaving, and then former, member country. Hence, the 2020 EU-UK Withdrawal Agreement as well as the 2020 EU-UK Trade and Cooperation Agreement and the 2023 Windsor Framework (and other specific agreements such as the 2021 UK-Euratom Nuclear Cooperation Agreement and the 2021 EU-UK Security of Information Agreement) constitute insightful materials to describe and understand how the European Union institutionally adapted to change.

References.

Buigut, S., & Kapar, B. (2023). How did Brexit impact EU trade? Evidence from real data. The World Economy, 46, 1566‑1581.

European Commission. (Online). Brexit and Ireland.

European Commission (2021). European Economic Forecast. Winter 2021 (Interim). Institutional paper 144.

Gilbert, M. (2020). European integration : A political history (Second edition.). Rowman & Littlefield.

International Monetary Fund. (2018). Euro Area Policies : Selected Issues. IMF Staff Country Reports, 2018(224).

Izzeldin, M., Muradoglu, G., Pappas, V., & Sivaprasad, S. (2025). Brexit and Its Impact on EU Financial Markets. International Journal of Finance & Economics.

Walker, N. (2021). Brexit timeline : Events leading to the UK’s exit from the European Union. House of Commons Library.

Suggested readings on the topic.

Davies, C. (2023). The impact of Brexit : Polity, politics, policy. Journal of European Integration, 45(6), 963‑969.

Howarth, D. and Quaglia, L. (2017) 'Brexit and the Single Financial Market', Journal of Common Market Studies Annual Review

Laffan, Brigid, and Stefan Telle. 2023. The EU’s Response to Brexit: United and Effective. Palgrave Macmillan.

Leruth, B., Gänzle, S., & Trondal, J. (2019). Differentiated Integration and Disintegration in the EU after Brexit : Risks versus Opportunities. Journal of Common Market Studies, 57(6), 1383‑1394.

Martini, M., & Walter, S. (2024). Learning from precedent : How the British Brexit experience shapes nationalist rhetoric outside the UK. Journal of European Public Policy, 31(5), 1231‑1258.

Pattyn, V., Gouglas, A., & De Leeuwe, J. (2021). The knowledge behind Brexit. A bibliographic analysis of ex-ante policy appraisals on Brexit in the United Kingdom and the European Union. Journal of European Public Policy, 28(6), 821‑839.

Schimmelfennig, F. (2018). Brexit : Differentiated disintegration in the European Union. Journal of European Public Policy, 25(8), 1154‑1173.

Schuette, L. A. (2021). Forging Unity : European Commission Leadership in the Brexit Negotiations. Journal of Common Market Studies, 59(5), 1142‑1159.

[1] International Monetary Fund (2018) Euro Area Policies: Selected Issues., p. 19

[2] European Commission (2021), p. 15

[3] Miss a reference.

[4] Buigut & Kapar (2023), p. 1577

[5] Izzeldin, Muradoglu, Pappas & Sivaprasad (2025), p. 22

[6] Miss a reference.

[7] European Commission (Online). Brexit and Ireland.

[8] As predicted by the International Monetary Fund (2018), p. 5

[9] Miss another updated reference.

[10] Miss a reference.

[11] Izzeldin, Muradoglu, Pappas & Sivaprasad (2025), p. 22

[12] Ibid.