Public service contracts which are not covered by [rules on posted workers, or on the public transportation of passengers by road and rail] may be awarded only to undertakings which, at the time of the submission of the tender, have agreed in writing, by means of a declaration made to the contracting authority, to pay their staff …, for the performance of the service, a minimum hourly wage of at least EUR 8.62. The undertakings shall, in their declarations, state the nature of the commitment adopted by their undertaking in the context of the collective agreement and the minimum hourly wage which will be paid to the staff engaged for the performance of the services. The amount of the minimum hourly wage may be adapted in accordance with Paragraph 21, by means of a regulation adopted by the Ministry of Labour.
Contracting authorities may lay down special conditions relating to the performance of a contract, provided that these are compatible with Community law and are indicated in the contract notice or in the specifications. The conditions governing the performance of a contract may, in particular, concern social and environmental considerations (emphasis added).
By imposing, in such a situation, a fixed minimum wage corresponding to that required in order to ensure reasonable remuneration for employees in the Member State of the contracting authority in the light of the cost of living in that Member State, but which bears no relation to the cost of living in the Member State in which the services relating to the public contract at issue are performed and for that reason prevents subcontractors established in that Member State from deriving a competitive advantage from the differences between the respective rates of pay, that national legislation goes beyond what is necessary to ensure that the objective of employee protection is attained (C-549/13, at para 34, emphasis added).
Contracting authorities may lay down special conditions relating to the performance of a contract, provided that they are linked to the subject-matter of the contract within the meaning of Article 67(3) [ie linked to the specific process of production or a specific process in another stage of the life-cycle] and indicated in the call for competition or in the procurement documents. Those conditions may include economic, innovation-related, environmental, social or employment-related considerations (emphasis added).