Article 15 bis imposes a transparency requirement on all taxpayers regarding their official tax identification. It mandates that the Tax Card number, issued in accordance with Article 11, must be clearly stated on all business outputs. This includes all official correspondence, invoices, publications, contracts, and any other legal or commercial documents issued by the taxpayer. This provision facilitates the tracking of commercial activities and ensures that the Tax Authority and contracting parties can easily verify the tax registration status of an entity during any transaction.