Title: Withdrawal from the European Union
Content:   The UK formally left the EU on 31 January 2020, following on a public vote held in June 2016. However, the country benefitted from a transition period to give time to negotiate a trade deal between the UK and the EU. The British government led by David Cameron held a referendum on the issue in 2016; the electorate decided by a 3.8% majority to favour leaving the European Union. On 29 March 2017, arising from a decision by the Parliament of the United Kingdom, Prime Minister Theresa May invoked Article 50 in a letter to the President of the European Council, Donald Tusk. The UK ceased to be a EU member state as from 00:00, 1 February 2020 
Title: History of the European Union (2004–present)
Content:  On 1 February 2020 CET (31 January GMT), the United Kingdom left the European Union in accordance with Article 50 of the Treaty on European Union. Between then and 31 December 2020, a transition period was in operation that kept in place all other aspects of the relationship to allow businesses to prepare and for a free trade agreement to be negotiated. The EU–UK Trade and Cooperation Agreement was subsequently signed and has applied provisionally since 1 January 2021.
Title: Withdrawal from the European Union
Content:  occur on 29 March 2019. Subsequently, the UK sought, and was granted, a number of Article 50 extensions until 31 January 2020. On 23 January 2020, the withdrawal agreement was ratified by the Parliament of the United Kingdom, and on 29 January 2020 by the European Parliament. The UK left the EU on 31 January 2020 at 23:00 GMT ending 47 years of membership. Four territories of EU member states have withdrawn: French Algeria (in 1962, upon independence), Greenland (in 1985, following a referendum), Saint Pierre and Miquelon (also in 1985, unilaterally) and Saint Barthélemy (in 2012), the latter three becoming Overseas Countries and Territories of the European Union.
Title: Timeline of European Union history
Content:  ; 2016 – UK holds a Membership Referendum and votes to leave the European Union ; 2017 – Negotiations between UK and the EU officially started in June 2017 ; 2017 – Start of Brexit: On 29 March 2017, the Government of the United Kingdom invoked Article 50 of the Treaty on European Union. The UK was due to leave the EU on 29 March 2019 at 11 p.m. GMT, when the period for negotiating a withdrawal agreement was set to end ; 2020 – UK leaves the EU after the Brexit withdrawal agreement takes effect on 31 January 2020 at 11 p.m. GMT 
Title: Member state of the European Union
Content:  undertake the process of withdrawing from the European Union. This began when the government of the United Kingdom triggered Article 50 to begin the UK's withdrawal from the EU on 29 March 2017, following a June 2016 referendum, and the withdrawal was scheduled in law to occur on 29 March 2019. Subsequently, the UK sought, and was granted, a number of Article 50 extensions until 31 January 2020. On 23 January 2020, the Withdrawal agreement was ratified by the Parliament of the United Kingdom, and on 29 January 2020 by the European Parliament. The UK left the EU on 31 January 2020 at 23:00 GMT, ending 47 years of membership.
Title: European Union
Content:  Croatia became the 28th EU member. From the beginning of the 2010s, the cohesion of the European Union has been tested by several issues, including a debt crisis in some of the Eurozone countries, increasing migration from Africa and Asia, and the United Kingdom's withdrawal from the EU. A referendum in the UK on its membership of the European Union was held in 2016, with 51.9 per cent of participants voting to leave. The UK formally notified the European Council of its decision to leave on 29 March 2017, initiating the formal withdrawal procedure for leaving the EU; following extensions to the process, the UK left the European Union on 31 January 2020, though most areas of EU law continued to apply to the UK for a transition period which lasted until 23:00 GMT on 31 December 2020.
Title: International relations since 1989
Content:  the UK and the remaining European Union countries. The UK left the EU on January 31, 2020. The European Union went through several crises. The European debt crisis caused severe economic problems to several eurozone member states, most severely Greece. The 2015 migration crisis led to several million people entering the EU illegally in a short period of time. Many died at sea. Growing cynicism and distrust of the established parties led to a sharp rise in the 2014 European Parliament Elections in the vote shares of several eurosceptic parties, including the League in Italy, Alternative for Germany, and the Finns Party in Finland.
Title: 2015–2016 United Kingdom renegotiation of European Union membership
Content:  agreed by the UK Parliament. On 23 June 2016 the United Kingdom, on a national turnout of 72 per cent, voted by 51.9 per cent to 48.1 per cent to leave the European Union and indirectly reject the terms of the new agreement. The result received a variety of different reactions internationally and began the process of leaving by invoking Article 50 of the Treaty on European Union on 29 March 2017, and after three extensions to the Article 50 process on 31 January 2020 at 23:00 GMT in accordance with the result of the referendum the United Kingdom became the first EU member state to formally leave the bloc, ending 47 years of membership.
Title: History of the European Union
Content:   On 23 June 2016, the citizens of the United Kingdom voted to withdraw from the European Union in a referendum and subsequently became the first and to date only member to trigger Article 50 of the Treaty on European Union (TEU). The vote was in favour of leaving the EU by a margin of 51.9% in favour to 48.1% against. The UK's withdrawal was completed on 31 January 2020.
Title: History of Europe
Content:  European Union, 52% of voters voted to leave the EU, leading to the complex Brexit separation process and negotiations, which led to political and economic changes for both the UK and the remaining European Union countries. The UK left the EU on 31 January 2020. Later that year, Europe was affected by the COVID-19 pandemic. According to the Wall Street Journal in 2021 as Angela Merkel stepped down as the highly popular Chancellort of Germany after 16 years:"Ms. Merkel leaves in her wake a weakened Europe, a region whose aspirations to act as a third superpower have come to seem ever more unrealistic. When she 

Question: when did we decide to leave the eu?
Answer: 23 June 2016.