PDF Invoices in Portugal in 2026: Still Valid, and What Changes in 2027

The question I keep seeing in freelancer groups and in my inbox: "Do I need a digital signature on my invoices now?"

Short answer: no. Not in 2026.

The longer answer is worth reading if you invoice clients as a freelancer or run a small business in Portugal, because the rule has been announced and delayed three times, and the confusion about what is actually required right now is real and understandable.

What the law says today

Portugal's parliament adopted the 2026 State Budget on 27 November 2025 (Lei 73-A/2025). One of the things it did was postpone the qualified electronic signature requirement on PDF invoices from 1 January 2026 to 1 January 2027.

This is the third postponement of this requirement. The original target date was 1 January 2025. That moved to 1 January 2026. Now it is 1 January 2027.

The practical consequence for the rest of 2026 is simple: PDF invoices from AT-certified software remain fully valid without any qualified electronic signature. If your software generates invoices with ATCUD codes and QR codes (which it must if it is certified), your invoices are compliant. Nothing has changed, nothing is missing, nothing needs to be added.

Multiple tax and compliance sources confirm this, including KPMG's December 2025 tax news flash and the ASD International compliance briefing from the same month. The law is clear on the 2026 position.

What a "qualified electronic signature" actually is

The term sounds technical because it is technical, and the announcements about it have not always explained what problem it is solving.

A qualified electronic signature (QES) is an eIDAS-grade cryptographic signature that gets applied to a PDF at the moment of issue. It proves two things: who signed the document, and that the document has not been altered since. The certificate that enables this must come from an EU-listed Qualified Trust Service Provider (a "QTSP"), an accredited entity that verifies your identity and issues the signing credentials.

This is different from the ATCUD code and the Portaria 363/2010 hash chain that already exist on every invoice from AT-certified software. Those are a Portugal-specific integrity mechanism. They tie each document to a sequence and communicate it to the tax authority. They work, and they are the reason your invoices are valid right now.

The open question, which tax professionals and accountants are actively working through (it is in front of accountants right now), is whether the existing certified-software chain already satisfies what the 2027 requirement will technically demand, or whether a separate QES layer will be needed on top. Until the Portuguese tax authority publishes the final technical specifications, this is not settled.

Why the question keeps coming up

Three postponements in three years is a pattern that would confuse anyone paying attention.

The history is roughly this: the requirement was written into Portuguese law as part of a broader push toward structured electronic invoicing across the EU. The original deadline was ambitious. Businesses and software vendors were not ready. The AT delayed it. Then delayed it again. Then the 2026 budget delayed it a third time.

Each delay came with another round of announcements. Each announcement reached people who had missed the previous ones, or who remembered the first date but not the second. So now you have freelancers in groups asking whether they already needed to do something in January 2025, and others who know about 2027 but are unsure whether something was already supposed to happen in 2026.

The answer to all of those questions is the same: the requirement has not taken effect yet. The transition year is 2026, and the transition requirement is nothing you do not already have if you are on certified software.

What actually changes on 1 January 2027

From 1 January 2027, the market guidance (and the current direction from Portuguese law) is that PDF invoices will be expected to carry a qualified electronic signature. The details of how this works in practice depend on technical specifications that the authorities have not yet finalized.

What that likely means in practice for businesses, once the specifications are confirmed: invoicing software will need to integrate with a Qualified Trust Service Provider and apply a cryptographic signature to PDF invoices at the moment of issue. This happens at the software level, not at your level. You issue the invoice as you always have; the software adds the signature before the PDF is generated.

For the SAF-T accounting file (a separate requirement): mandatory annual submission was also postponed by Lei 73-A/2025. The first submission covering the 2026 fiscal year will be due in 2028. So that clock has not started yet either.

For Descodify users

Descodify is AT-certified invoicing software. Every invoice you issue through it already has an ATCUD code, a QR code, and the Portaria 363/2010 hash chain. For the purposes of 2026, that is everything the law requires. Your PDFs are valid.

For 2027, we are tracking the technical specifications as they come from the AT and the Portuguese legislature. When those specifications are confirmed, we plan to handle whatever the software needs to do at our end. The goal is that you will not need to obtain a separate certificate, register with a trust provider, or change how you work.

That said, this is a new requirement and the details are not final. We will communicate what is coming well before 1 January 2027.

What you should actually do right now

Nothing, if you are already using certified invoicing software.

If you are not on certified software, that is the actual gap. The ATCUD code requirement has been in force since January 2023. An uncertified tool cannot produce a compliant invoice regardless of the QES question. The AT certification requirement is the one that actually bites today, and it has since 2023.

The QES story is real, and 2027 will require adaptation. But the question for the rest of 2026 is whether your software is certified, not whether it signs PDFs.

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Sources: Lei 73-A/2025 (Orçamento do Estado 2026, adopted 27 November 2025); KPMG Tax News Flash, December 2025; ASD International compliance briefing, 2025; rtcsuite.com e-invoicing Portugal reference, 2025-2026.