The European Union (Notification of Withdrawal) Act 2017 (c. 9) was an Act of the Parliament of the United Kingdom to empower the Prime Minister to give to the Council of the European Union the formal notice – required by Article 50 of the Treaty on European Union – for starting negotiations for the United Kingdom's withdrawal from the European Union. It was passed following the result of the 2016 United Kingdom European Union membership referendum held on 23 June in which 51.9% of voters voted to leave the European Union.