Electronic Invoicing in Portugal 2025

Complete guide on implementation and legal compliance

Electronic invoicing represents a fundamental transformation in the way companies and public bodies manage their administrative and financial processes. In Portugal, this reality has become even more relevant with the application of European regulations that establish strict standards for the issuance, transmission, and receipt of electronic documents.

Digital signature and authenticity requirements

The authenticity and integrity of electronic documents is guaranteed by qualified digital signature or qualified electronic seal systems. The qualified electronic signature is a unique and non-transferable identification generated from certified secure devices (QSCD – Qualified Signature Creation Devices).

This cryptographic system unambiguously confirms the authorship of the document, identifies the company responsible for issuing it and guarantees the integrity of the data. These mechanisms allow the holder of the document to claim authorship, providing a legal evidentiary value comparable to that of a traditional handwritten signature.

The qualified electronic seal represents the digital and secure version of the company's stamp. Unlike the qualified electronic signature, this mechanism only identifies an organisation (legal entity) and not an individual document holder. This solution makes it possible to automate the signature process without human intervention, optimising organisational workflows.

When using electronic data interchange (EDI) systems via the AS2 protocol, the signing of documents is optional, as the transport protocol already uses X.509 certificates to ensure the security of the transmission.

Invoice certification aims to unequivocally identify the entity issuing the invoice, i.e. the co-contractor, so the signature or seal used on the invoice must be issued in the name of the entity actually issuing the invoice.