Portugal has been about to require signed PDF invoices for years. Under current law, plain PDF invoices are accepted as valid electronic invoices only until 31 December 2026. From 1 January 2027 they are expected to need a qualified electronic signature or seal. But on 8 October 2026 the government submitted a draft 2027 State Budget that would push the deadline back once more, to 1 January 2028. If you send or receive invoices in Portugal, here is what the rule actually says, where things stand, and what to do while Parliament decides.
What the rule requires
The underlying law is Decreto-Lei n.º 28/2019, which governs how invoices are processed and stored. Article 6 requires businesses to guarantee the authenticity of origin, integrity of content and legibility of their invoices from issue until the end of the retention period.
For invoices sent electronically, Article 12 lists ways to meet that requirement, including:
- A qualified electronic signature
- A qualified electronic seal under the EU eIDAS Regulation (EU) No 910/2014
- An EDI exchange between parties who have signed an agreement based on the European model EDI agreement
The law also says the invoicing software must be able to check that the issuer's certificate was not revoked, expired or suspended on the date of issue.
A qualified signature or seal relies on a qualified certificate from a trust service provider on the EU trusted lists. A drawn signature or a typed name on a PDF does not count. If the difference is unclear, see digital signatures vs electronic signatures.
A deadline that keeps moving
According to KPMG, the requirement was first due in July 2021 and has been postponed ever since. The most recent steps:
- 27 November 2025: Parliament approved the 2026 State Budget, moving the requirement from 1 January 2026 to 1 January 2027 (Sovos).
- 30 December 2025: Law No. 73-A/2025 confirmed that PDF invoices remain accepted until 31 December 2026.
- 8 October 2026: The draft 2027 State Budget went to Parliament. Article 77(3) would keep PDF invoices valid for all tax purposes until 31 December 2027 (Comarch, Fiscal Solutions).
The important point is that the 2028 date is still a proposal. Until the budget is approved and published, the legal deadline remains 1 January 2027. Portuguese budgets are normally voted in late November, so the answer should come within weeks.
What the delay would not change
The extension only covers whether an unsigned PDF counts as a valid electronic invoice. Portugal's other invoicing rules stay in force:
- ATCUD, the unique document code on each invoice
- The mandatory QR code with fiscal data
- SAF-T (PT) invoicing data reported to the Tax Authority
- Certified invoicing software where the law requires it
- Rules on numbering, retention and records
A delay also does not create a new obligation to send structured e-invoices from 2028. EU-wide structured invoicing is a separate track, coming through ViDA.
How to prepare either way
Planning around a delay that has not been approved is risky. A sensible approach is to be ready for 1 January 2027 and treat any extra year as a buffer.
- Find out how your invoices are made. Most Portuguese suppliers issue PDFs from certified invoicing software. Ask your vendor whether it can apply a qualified seal automatically and what it costs.
- Prefer a seal for company invoices. A qualified electronic seal belongs to the organisation rather than a person, which suits automated, high-volume invoicing.
- Do not edit the PDF after it is sealed. Any change, even adding a page or a note, breaks the signature. Merge, annotate or stamp copies only, never the version you send.
- Check incoming invoices. If you receive Portuguese invoices, open the signature panel and confirm the certificate is valid. See how to verify a digital signature in a PDF and, if something looks wrong, why a PDF signature shows as invalid.
- Keep the signed original. Archive the file exactly as received so the signature can still be checked later. Long-term validation and timestamps explains why that matters years down the line.
Why signed invoices are worth it anyway
Even without a mandate, a sealed invoice is harder to fake. Invoice fraud often relies on altered PDFs with changed bank details, as covered in invoice fraud and business email compromise. A valid seal from a known supplier is a quick check that the file has not been touched since it was issued.
Takeaway
Plain PDF invoices are legal in Portugal until 31 December 2026, and possibly until 31 December 2027 if Parliament approves the budget proposal. Either way, the direction is clear: invoices sent as PDFs will need a qualified signature, a qualified seal or a formal EDI setup. Talk to your invoicing software vendor now. For everyday work on unsigned copies, such as merging statements or adding notes for your accounts team, you can use Docento.app in your browser, with your files staying on your device.
