E-invoicing in Portugal: The 2026 compliance guide for finance teams

E-invoicing in Portugal has a lot of moving parts. Business-to-government (B2G) e-invoicing is mandatory for all suppliers to public administration as of January 2026, with large enterprises in scope since 2021 and SMEs and micro-enterprises now covered under a phased rollout. While business-to-business (B2B) structured e-invoicing isn’t required yet, Portugal has committed to extending it under VAT in the Digital Age (ViDA). The groundwork is already in place, as every invoice issued in Portugal must have a unique document code (ATCUD) and QR code, is created using tax authority-certified software and is reported monthly through Standard Audit File for Tax (SAF-T).

Here’s what’s required in 2026, how ATCUD, QR codes and SAF-T work, what the B2G mandate means for suppliers and where the B2B mandate stands.

Key highlights

• B2G e-invoicing is mandatory in the national CIUS-PT format. Large companies have been required to comply since January 2021, and the mandate extends to medium, small and micro-enterprises starting January 1, 2027.
• B2B structured e-invoicing is not yet mandatory, but Portugal has committed to extending it under the EU’s ViDA framework.
• SAF-T Billing is submitted monthly to the Autoridade Tributária e Aduaneira (AT) by the 5th of the following month.
• From January 1, 2027, PDF invoices used for B2B and B2C transactions will require a Qualified Electronic Signature (QES). Until December 31, 2026, PDFs remain valid without one.

What does Portugal require for e-invoicing in 2026?

Portugal mandates B2G e-invoicing for all suppliers selling to its public sector. B2B structured e-invoicing isn’t mandatory yet, but the direction is set.

B2G e-invoicing

All suppliers to Portuguese public administration are required to issue structured e-invoices. The mandate has been rolled out in phases:

• January 2021: Large companies (more than 250 employees or annual turnover above €50 million or balance sheet above €43 million)
• January 1, 2026: Small, mid-sized and micro-enterprises. PDF invoices with QR codes issued by certified software are accepted as valid e-invoices through December 31, 2026. From January 1, 2027, suppliers must issue structured CIUS-PT invoices or apply a Qualified Electronic Signature to PDF invoices

B2G invoices are issued in CIUS-PT format, Portugal’s national implementation of the European Union standard EN 16931 using UBL 2.1. B2G invoices are issued in CIUS-PT format, Portugal's national implementation of the European Union standard EN 16931 using UBL 2.1. Suppliers can transmit invoices through the FE-AP platform operated by eSPap or through other approved service providers and portals designated by the contracting public entity. Portal BASE is the public procurement transparency platform where contract information is published.

B2B invoicing

Portugal does not currently impose a general structured e-invoicing mandate for domestic B2B transactions. However, domestic invoice processing and reporting remain subject to extensive controls, and a wider B2B mandate may happen in line with ViDA’s initiatives.

Taxpayers within the scope of Portugal’s certified-software rules must use Tax and Customs Authority-certified invoicing software. This generally covers taxpayers subject to Portuguese invoicing rules that use invoicing software, have organized accounting or have opted for it, and exceeded €50,000 in turnover in the prior calendar year.

Invoices and other fiscally relevant documents are generally subject to the ATCUD requirement, which requires obtaining and featuring an ATCUD code on each invoice. QR-code requirements apply to documents issued using AT-certified invoicing software. 

Taxpayers subject to Portugal’s invoice-data communication obligation must transmit invoice data to AT electronically. Permitted methods include real-time transmission, submission of a file structured on the SAF-T (PT) format, and direct entry in the Portal das Finanças.

What is ATCUD, and why does every Portuguese invoice need it?

Código Único do Documento, shortened to ATCUD, is a unique document identifier that appears on every invoice issued in Portugal. It’s mandatory for e-invoices. The code is made up of two parts:

1. A validation code assigned by the AT when the business registers an invoice series
2. A sequential document number within that series. 

Together, they form the ATCUD printed on the invoice and are used to trace invoices. The AT can track every invoice back to the certified software that issued it, and the series it belongs to and its position in the sequence.

Businesses register their invoice series through the AT’s e-Fatura portal or via API, and the AT returns validation codes in batches. Each invoice issued then receives its unique ATCUD, which is also embedded in the invoice’s QR code and included in the SAF-T Billing file.

If an invoice is missing its ATCUD, it’s technically non-compliant. AT uses the ATCUD as a core traceability mechanism for audits, cross-referencing it against SAF-T data and e-Fatura records.

What is the QR code requirement on Portuguese invoices?

Since January 1, 2022, every invoice issued by AT-certified software in Portugal is required to include a QR code. The QR code gives purchasers a machine-readable way to communicate invoice data to AT using the e-Fatura app when the business’s Número de Identificação Fiscal (NIF) tax identifier was not included at issuance. It also supports AT’s invoice-control framework.

What is SAF-T (Portugal), and how does monthly reporting work?

Portugal was early to adopt the Organisation for Economic Co-operation and Development’s Standard Audit File for Tax, implementing it in 2008. The Portuguese version, SAF-T (PT), is a structured XML format that captures invoicing and accounting data.

The most immediate compliance obligation is the SAF-T Billing file, which every VAT-registered business operating in Portugal is required to submit monthly to the AT by what’s often the fifth day of the following month, but businesses can use the AT’s obligation calendar to plan for filing dates.

The SAF-T Billing file contains every invoice, credit note and debit note issued during the reporting month, including invoice numbers, dates, customer NIFs, line item details, VAT rates and amounts, ATCUD codes and totals. 

Invoice data can be communicated to Portugal’s Tax Authority through the e-Fatura system using real-time web-service transmission, a multidocument file structured on the SAF-T (PT) format and submitted through the Portal das Finanças or its command-line application, or direct entry in the portal. 

SAF-T Accounting (the full general ledger) is a separate requirement. It was originally scheduled for fiscal year 2025 but has been postponed to fiscal year 2027, with the first submission due in 2028.

What’s coming next: B2B mandate, QES and SAF-T Accounting

Three upcoming developments are worth tracking:

B2B structured e-invoicing mandate

Portugal does not currently have a general domestic B2B structured e-invoicing mandate. At EU level, ViDA enables Member States to introduce domestic e-invoicing requirements without the former EU derogation process. 

According to the European Commission, ViDA will introduce electronic invoicing-based digital reporting for specified intra-EU cross-border B2B transactions from 2030, using the European e-invoicing standard. 

Finance teams that are already issuing structured invoices for B2G and have clean master data, certified software and SAF-T reporting in place will find the transition straightforward when it arrives. Those still relying on PDF-by-email for B2B might face a larger implementation project.

Qualified Electronic Signature (QES) for PDF invoices

PDF invoices currently remain valid for B2B and B2C transactions in Portugal without a digital signature, but only until December 31st, 2026. 

Starting January 1, 2027, all PDF invoices will require a Qualified Electronic Signature (QES) or a Qualified Electronic Seal issued by a certified third-party provider. This requirement has been postponed multiple times (originally scheduled for 2024, then 2025, then 2026) but the current 2027 deadline is set in the 2026 State Budget.

Businesses that switch to structured formats (XML, EDI) or use the Peppol network for B2B invoicing aren’t affected by the QES requirement, as it applies specifically to PDF invoices.

SAF-T Accounting

The mandatory SAF-T Accounting submission (covering the full general ledger) has been deferred to fiscal year 2027, with the first filing due in 2028, per the 2026 State Budget. This is separate from the monthly SAF-T Billing file, which is already mandatory.

How to prepare for Portugal’s e-invoicing requirements

Most of the compliance groundwork is in confirming that the controls already in place are working correctly and that the upcoming deadlines don’t catch your team off guard. Here’s where to start.

1. Confirm your invoicing software is AT-certified: If your business falls within Portugal’s certified-software rules, the software that issues invoices must be registered with the Autoridade Tributária. Check your certification status on the Portal das Finanças.
2. Audit your ATCUD generation: Every invoice needs a unique ATCUD, which means your invoice series must be registered with the AT through the e-Fatura portal or API. Verify that validation codes are being assigned correctly and that the ATCUD appears on each issued document.
3. Verify QR codes are present and accurate: QR codes have been mandatory on invoices issued by certified software since January 2022. Confirm that your QR codes encode the required fields, including issuer NIF, ATCUD, VAT totals and gross totals, and test them against the AT’s validator.
4. Review your SAF-T Billing submission process: Monthly SAF-T Billing files are usually due by the fifth of the following month. If your team is still submitting manually through the Portal das Finanças, map out whether real-time web-service transmission or automated file submission would reduce the risk of missed deadlines.
5. Plan for the QES requirement on PDF invoices: Starting January 1, 2027, all PDF invoices used for B2B and B2C transactions will need a Qualified Electronic Signature or Qualified Electronic Seal. If your business still issues PDF invoices, evaluate whether to adopt a QES provider or switch to structured formats like XML or EDI, which aren’t subject to the QES rule.
6. Prepare for SAF-T Accounting: The full general ledger submission has been deferred to fiscal year 2027, with the first filing due in 2028. Start reviewing your chart of accounts and GL data quality now.
7. Monitor the B2B e-invoicing mandate: Portugal hasn’t set a final effective date for mandatory B2B structured e-invoicing, but the direction is clear under the EU’s ViDA framework. Finance teams that already have clean master data, certified software and SAF-T reporting in place will have a shorter runway when the requirement lands.

Disclaimer: E-invoicing regulations in Portugal are actively evolving. The information in this guide reflects publicly available guidance as of mid-2026. Finance teams making compliance decisions based on these requirements are encouraged to verify current status with the Autoridade Tributária e Aduaneira or seek professional advice.