Until 2020, no member state had ever withdrawn or been suspended from the EU, though some dependent territories or semi-autonomous areas had previously left. The UK government invoked Article 50 of the Treaty on European Union on 29 March 2017 to formally initiate the Brexit process. Completion occurred on 31 January 2020 (at 23:00 ), with all other arrangements remained in place during a transition period, which ended at 23:00 GMT on the 31 December 2020, while future trading arrangements were discussed.