Currently, e-invoicing for business-to-business (B2B) transactions in Portugal is not mandatory. However, the Portuguese Tax Authority requires resident and non-resident taxpayers to transmit invoice data electronically using certified invoicing software that can generate invoices with a unique document code (ATCUD) and a QR code. All resident taxpayers are also required to submit SAF-T reporting information on a monthly basis, including sales invoices.
From January 1, 2026, businesses using PDF invoices for transactions not covered by the e-invoicing mandate must include a Qualified Electronic Signature or a Qualified Electronic Seal, issued by a certified third-party provider.