What is the ATCUD
The unique document code (ATCUD) is a code that allows the unique identification of a document, regardless of its issuer, the type of document and the used sequence. The ATCUD, as defined in Article 3 of Ordinance No. 195/2020, of August 13, results from the concatenation between the validation code assigned to the sequence and the sequential number of the document within that sequence, with the format "ATCUD: Validation Code-Sequential Number".
The ATCUD must be created at the time the document is issued, by the computer program or other electronic means, and must appear on every page of the tax document to which it applies. On pages where the QR Code is displayed, the ATCUD must be positioned immediately above the QR Code.
The unique document code (ATCUD) and the QR code must be visible and perfectly readable, regardless of the medium used to display it to the respective recipient.
Both ATCUD and the QR code aim to prevent the informal economy, avoid fraud and tax evasion, and promote a simplified way of reporting invoices.