1. Member States shall adopt the laws, regulations and administrative provisions necessary to comply with this Directive by 21 May 2018, or shall ensure that the social partners introduce the required provisions by way of agreement by that date. Member States are required to take the necessary steps enabling them to guarantee the results imposed by this Directive. They shall immediately inform the Commission thereof.
2. When Member States adopt the measures referred to in paragraph 1, 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 the Member States.