Any economic operator wishing to take part in a public contract may be requested to prove its enrolment, as prescribed in his Member State of establishment, on one of the professional or trade registers or to provide a declaration on oath or a certificate as described in Annex IX A for public works contracts, in Annex IX B for public supply contracts and in Annex IX C for public service contracts.
In procedures for the award of public service contracts, insofar as candidates or tenderers have to possess a particular authorisation or to be members of a particular organisation in order to be able to perform in their country of origin the service concerned, the contracting authority may require them to prove that they hold such authorisation or membership.