Brexit () is the prospective withdrawal of the United Kingdom (UK) from the European Union (EU). In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU, out of a turnout of 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on the European Union. The UK is thus due to leave the EU on 29 March 2019. Prime Minister Theresa May announced that the UK would not seek permanent membership of the single market or the customs union after leaving the EU and promised to repeal the European Communities Act of 1972 and incorporate existing European Union law into UK domestic law. A new government department, the Department for Exiting the European Union (DExEU), was created in July 2016, with Eurosceptic David Davis appointed its first Secretary of State. Negotiations with the EU officially started in June 2017. The UK joined the European Communities (EC) in 1973, with membership confirmed by a referendum in 1975. In the 1970s and 1980s, withdrawal from the EC was advocated mainly by Labour Party members and trade union figures. From the 1990s, the main advocates of withdrawal were the newly founded UK Independence Party (UKIP) and an increasing number of Eurosceptic Conservative Party members. There is strong agreement among economists and a broad consensus in existing economic research that Brexit is likely to reduce UK's real per-capita income in the medium and long-term. Studies on effects that have already materialised since the referendum show annual losses of £404 for the average British household and a loss of 1.3% of UK GDP. Brexit is likely to reduce immigration from European Economic Area (EEA) countries to the UK, and poses challenges for UK higher education and academic research. The size of the "divorce bill", Britain's international agreements, relations with the Republic of Ireland, and the borders with France and between Gibraltar and Spain are uncertain. The precise impact on the UK depends on whether it would be a "hard" Brexit or a "soft" Brexit.