ATCUD and communication of series

As of 1 January 2023, the Single Document Code (ATCUD) will become mandatory both in invoices and in documents considered fiscally relevant. Therefore, all issuers in national territory will have to adjust their invoicing systems according to the new requirements of the Tax and Customs Authority.

ATCUD is a unique code assigned by the Autoridade Tributária e Aduaneira (AT) covering not only the validation code of the series but also the sequential number of the document within the series, resulting in the following format “ATCUD: Validation Code-Sequential Number”.

As such, ATCUD must be present on all invoices and tax-relevant documents that are issued by any of the following means of processing:

• Billing software, in which include the different billing applications provided by the Tax and Customs Authority (AT);
• Other electronic means such as cash registers, electronic terminals or even electronic scales;
• Pre-printed documents from legally authorised printers.

Also in this context, in order to obtain the ATCUD, invoicing software users are required to communicate to the Tax Authority (AT) the invoicing series they will use to issue invoices for each establishment and means of processing used during the tax year.