Article L3133-6 of the French Public procurement code
A shared solution, made available by the State and known as the “public invoicing portal”, enables invoices to be submitted, received and transmitted in electronic form. For the implementation of the obligations resulting from sub-section 1 of this section, the following use the public invoicing portal: 1° The State, local authorities and public establishments; 2° Holders of concession contracts concluded with a conceding authority mentioned in 1°.