In Germany, the VAT number is known as the UST-ID (Umsatzsteuer-Identifikationsnummer). VAT (Value Added Tax) is the international designation for this term. Companies must always include their tax identification on their invoices. It often makes sense to also include the recipient’s tax identification. If you are sending an invoice internationally, known within the EU as an intra-Community service or delivery, this will also be the VAT number.