If UID numbers have been inserted after the invoice was created and the verification of your UID was successful, the future invoices will be issued tax-free. Unfortunately we have no possibility to check the VAT retroactively. Therefore we ask you to send us a confirmation that you already had a valid UID in the previous year (notification of the issuing of the VAT ID).

Learn how to insert the VAT number here
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You can send the confirmation that you already had a valid UID to support@yumpu.com