Article 20 (1) of the Treaty on the Functioning of the European Union states that;
Citizenship of the Union is hereby established. Every person holding the nationality of a Member State shall be a citizen of the Union. Citizenship of the Union shall be additional to and not replace national citizenship.
All nationals of Member States are citizens of the union. "It is for each Member State, having due regard to Community law, to lay down the conditions for the acquisition and loss of nationality.