Article 51 of the EEC Treaty provides for the adoption of such measures in the field of social security as are necessary to provide freedom of movement for workers. The Treaty also provides for the right of EU nationals to become established and to provide services in any member state of the EU (and the European Economic Area arising out of the European Economic Area Agreement). In addition the Treaty of the European Union has as one of its objectives the abolition of obstacles between member states to the free movement of persons and services.
Arising out of Article 51 of the Treaty, Regulation (EEC) No. 1408/71 was adopted. It provides for co-ordination of social security schemes for employed and self-employed persons and members of their families moving within the European economic area. Under this Regulation an employed or self-employed person is generally subject to the social insurance system of the member state in which he is employed both for the payment of contributions and the payment of benefits.
Special rules apply to workers who are posted by their employer in one member state to work for a period of less than one year for him in another member state. Similar provisions also apply to persons who are normally self-employed who perform work, again for a period of less than one year, in the territory of another member state. Any extension of such periods of work in another member state beyond 12 months is subject to the agreement of the member state in which the person works. These special provisions do not apply to workers who emigrate to another EEA state to seek work on their own account. Such workers are subject to the social security legislation of the member state in which they work.