Article R2393-40 of the French Public procurement code
A subcontractor who has been accepted and whose payment conditions have been approved may assign or pledge all or part of his claim, up to the amount of the services paid directly to him. A copy of the original of the contract or of the certificate of transferability provided for in article R. 2191-46 or, where applicable, of the special deed provided for in article R. 2393-27 designating a subcontractor…