1. Member States shall adopt and publish the laws, regulations and administrative provisions necessary to comply with this Directive by 5 December 2011, or shall ensure that the social partners introduce the necessary provisions by way of an agreement, whereby the Member States must make all the necessary arrangements to enable them to guarantee at any time that the objectives of this Directive are being attained. They shall forthwith inform the Commission thereof.

2. When Member States adopt these measures, they shall contain a reference to this Directive or shall be accompanied by such reference on the occasion of their official publication. The methods of making such reference shall be laid down by Member States.