 The Maastricht Treaty of 1992 required that EU member states join the euro.However, the treaty gave Denmark the right to opt out from participation, which they subsequently did following a referendum on 2 June 1992 in which Danes rejected the treaty.Later that year Denmark negotiated the Edinburgh Agreement, under which Denmark was granted further opt-outs, which led to the Maastricht Treaty being accepted in a referendum on 18 May 1993.