The provisions of the Agreement between the European Community and its Member States, of the one part, and the Swiss Confederation, of the other, on the free movement of persons, signed in Luxembourg on 21 June 1999, concerning the equal treatment of employees must be interpreted as precluding the legislation of a Member State, such as the legislation at issue in the main proceedings, under which a resident national with unlimited liability to income tax who has exercised the right to freedom of movement in order to work as an employee on a part-time basis in the teaching profession for a legal person governed by public law established in Switzerland is denied a tax exemption in respect of the income from that employment whereas such an exemption would be granted if that person had been so employed by a legal person governed by public law established in that Member State, in another Member State of the European Union or in another State to which the Agreement on the European Economic Area of 2 May 1992 applies.