Article 12 5.

Any period regarded as equivalent under the legislation of two or more Member States shall be taken into account only by the institution of the Member State to whose legislation the person concerned was last compulsorily subject before that period. In the event that the person concerned was not compulsorily subject to the legislation of a Member State before that period, the latter shall be taken into account by the institution of the Member State to whose legislation the person concerned was compulsorily subject for the first time after that period.