Portugal is a pioneer in SAF-T implementation for tax control, having adopted this international OECD standard in 2008 — well ahead of most European countries. The SAF-T (PT) file is central to fiscal compliance for all businesses, including e-commerce operators, and the Autoridade Tributária (AT) enforces its requirements with increasing rigor through automated validation and cross-referencing systems.
What is SAF-T (PT)?
The SAF-T (Standard Audit File for Tax Purposes) is an XML file containing all accounting and invoicing data in a standardized, machine-readable format. Portugal has two main types: the invoicing SAF-T, which must be submitted monthly to the AT by the 5th of the following month and contains all invoices, credit notes and other commercial documents issued; and the accounting SAF-T, submitted annually together with the IES declaration by July 15th. The format follows the OECD standard adapted to Portuguese specificities through Portaria 321-A/2007 and subsequent updates. Each document in the SAF-T must include a unique hash code that ensures data integrity and prevents tampering.
AT-certified software requirements
All companies in Portugal are required to use invoicing software certified by the Autoridade Tributária. The certification process ensures the software meets technical requirements, including compliant SAF-T file generation, valid invoice series assignment and the impossibility of modifying or deleting issued documents. For e-commerce operators, this means the online sales platform must integrate with certified software, either through native modules (available for WooCommerce, PrestaShop and Magento) or via API with solutions like Moloni, InvoiceXpress, PHC or Sage. The AT maintains a public registry of certified software that sellers should consult before choosing their invoicing solution.
eSPap and B2G electronic invoicing
Electronic invoicing is mandatory for public procurement contracts (B2G) through the eSPap platform (Entidade de Serviços Partilhados da Administração Pública). Since 2021, all companies supplying goods or services to the Portuguese state must issue structured electronic invoices in the CIUS-PT format, based on the European standard EN 16931. Submission is done through the FE-AP platform, and non-compliance can result in invoice rejection and payment delays. This requirement applies regardless of the contract value.
The future of e-invoicing in Portugal
Portugal is progressively expanding electronic invoicing obligations. Real-time invoice communication to the AT is evolving, with the goal of creating a continuous transaction control system similar to what already exists in countries like Italy and Spain. The European trend points toward mandatory structured electronic invoicing for B2B transactions as well, following the ViDA (VAT in the Digital Age) initiative. E-commerce businesses should prepare for this transition by investing in updated software, automated processes and robust API integrations. Zunapro implements compliant SAF-T invoicing solutions and prepares e-commerce businesses for upcoming electronic invoicing obligations in Portugal.
