Article 12 1.

Any measure implementing this Chapter, as regards workers, shall cover all benefits under occupational social security schemes derived from periods of employment subsequent to 17 May 1990 and shall apply retroactively to that date, without prejudice to workers or those claiming under them who have, before that date, initiated legal proceedings or raised an equivalent claim under national law. In that event, the implementation measures shall apply retroactively to 8 April 1976 and shall cover all the benefits derived from periods of employment after that date. For Member States which acceded to the Community after 8 April 1976, and before 17 May 1990, that date shall be replaced by the date on which Article 141 of the Treaty became applicable in their territory.