1. The Member States shall take all necessary steps to ensure that:

(a) where a vesting period or a waiting period, or both, is applied, the total combined period shall under no circumstances exceed three years for outgoing workers;

(b) where a minimum age is stipulated for the vesting of pension rights, that age shall not exceed 21 years for outgoing workers;

(c) where an outgoing worker has not yet acquired vested pension rights when the employment relationship is terminated, the supplementary pension scheme shall reimburse the contributions paid by the outgoing worker, or paid on behalf of the outgoing worker, in accordance with national law or collective agreements or contracts, or, where the outgoing worker bears the investment risk, either the sum of the contributions made or the investment value arising from these contributions.

2. Member States shall have the option of allowing the social partners to lay down different provisions by collective agreement, to the extent that those provisions provide no less favourable protection and do not create obstacles to the freedom of movement for workers.