KSeF vs SdI vs FACe vs AT — e-invoice systems compared
Italy, Portugal, Poland and Spain each run a different mandatory e-invoice system. A practical comparison for procurement teams operating from Lisbon and managing cross-border spend with the Iberian peninsula, Italy and central Europe.
Four systems, one direction of travel
Italy's Sistema di Interscambio (SdI) was the EU pioneer: mandatory B2B e-invoicing since January 2019, FatturaPA XML format, qualified certificate or business signature. Portugal runs the Autoridade Tributária e Aduaneira (AT) regime via Portal das facturas with monthly SAF-T (PT) submission, structured invoice documents carrying an ATCUD code and a verification QR. Poland's Krajowy System e-Faktur (KSeF) reaches full B2B mandate in February 2026, FA(2) XML format, structured clearance through the central hub. Spain operates FACe for B2G (Facturae format) plus SII (Suministro Inmediato de Información) for real-time VAT submission to the AEAT, IVA 21%.
The format differs across the four — FatturaPA XML, UBL, FA(2), Facturae, SAF-T — but the direction of travel is the same: structured XML, real-time or near-real-time clearance, no PDF-only invoicing, archival for 10 years. Each system is anchored in the national tax authority rather than the EU Commission, which is why harmonisation has been slow. The EU's VAT in the Digital Age (ViDA) initiative aims to align the rules over the 2026–2030 horizon.
Side-by-side cheat-sheet for Portugal-based buyers
Italy SdI: FatturaPA XML, mandatory B2B since 2019 and B2G, IVA 22%, signature with qualified certificate or business signature, 10-year retention. Portugal AT/Portal das facturas: structured invoice document (no specific national XML but commonly UBL or Facturae-PT), monthly SAF-T (PT) submission, ATCUD code, QR for AT verification, IVA 23% standard (13% reduced, 6% zero-rated), 10-year retention. Poland KSeF: FA(2) XML, full B2B mandate from February 2026, VAT 23%, central clearance, 10-year retention. Spain FACe (B2G) + SII real-time (within 4 days of invoice issuance or receipt), IVA 21%, Facturae format for B2G, 4-year VAT retention but 10-year for commercial documents.
Across all four: SEPA Net 30 or SEPA Net 45 is the practical payment term for B2B; cross-border payments add 1-3 days. SEPA Instant (under 10 seconds, 24/7) is available in Portugal through CGD, Millennium bcp, BPI, Novo Banco and Santander Totta, but the practical B2B default is still SEPA Credit Transfer with 1-day clearing.
Implications for buyers operating from Portugal
Even if you only buy merchandise under IVA 23% via Portal das facturas (AT), the cross-border dimension of your supply chain affects invoicing. As your group expands into Italy, Spain or Poland, or as you procure from a supplier with fulfilment in those markets, you increasingly need suppliers who can issue compliant e-invoices in all four systems — same SKU master, four different XML wrappers, no manual rekeying.
From the Lisbon hub we issue native compliant e-invoices in all four systems. The master data (SKU, EUR unit price, decoration method, country of origin) is shared; the invoice envelope is local. The buyer's AP team in Lisbon, Madrid, Milan or Warsaw receives a compliant invoice in the local format with no manual translation required.
For a Portuguese buyer with a single supplier relationship, the practical question is: does the supplier issue AT-compliant invoices via Portal das facturas on the day of delivery? The answer from the Lisbon hub is yes, with the ATCUD code and QR on every invoice. The secondary question is: does the supplier's data sheet tie cleanly to the buyer's accounting system (SAP, Primavera, PHC)? The answer is yes, with line-item reconciliation.
The Portugal angle: AT, SAF-T and the new SAF-T-PT changes
Portugal's Autoridade Tributária e Aduaneira (AT) administers IVA 23% via the Portal das facturas system and the monthly SAF-T (PT) file. SAF-T (Standard Audit File for Tax) is the structured export that Portuguese companies generate monthly from their accounting system and submit to AT for audit purposes. The SAF-T-PT schema has been stable for several years, with the most recent changes covering e-invoicing structures and the SAF-T-AO (annual opening) and SAF-T-FR (annual closing) variants.
The ATCUD (Código Único de Documento) is the unique identifier assigned by AT to every invoiced document. The QR code on the invoice allows AT verification by any party. The ATCUD ties the invoice to the buyer's and seller's AT-issued certificates and to the underlying VAT return.
The 2024-2026 evolution has been the tightening of real-time reporting requirements for certain categories of invoices (high-value transactions, cross-border services, intra-EU acquisitions). For corporate merch, which is typically a domestic B2B transaction, the regime is stable and well-understood.
The Italy angle: SdI and FatturaPA XML
Italy's SdI (Sistema di Interscambio) was the EU pioneer, mandatory B2B e-invoicing since January 2019. The format is FatturaPA XML, a structured document with detailed line-item, VAT rate (IVA 22% standard, 10% / 5% / 4% reduced, 0% zero-rated), and IdentificativoSdI identifier. The invoice is signed with a qualified certificate or business signature and routed through SdI to the buyer's Codice Destinatario or PEC (certified email) inbox.
For Portugal-based buyers procuring in Italy, the practical question is whether the Italian supplier can issue SdI-compliant invoices with the Codice Destinatario (7-character recipient code) or PEC. From the Milan side of our network, the answer is yes. The Italian invoice is then re-invoiced through Portugal as a triangular transaction under the EU VAT rules, with IVA 23% documented via the reverse-charge mechanism in the Portuguese buyer's AT return.
The Poland angle: KSeF and FA(2) XML
Poland's KSeF (Krajowy System e-Faktur) reaches full B2B mandate in February 2026. The format is FA(2) XML, a structured invoice document with detailed line items, VAT rates (23% standard, 8% / 5% reduced, 0% / zw / np / oo for exemptions and zero-rates), and a KSeF number assigned at the moment of clearance. The central hub issues the number in real time; clearance is near-instant.
For Portugal-based buyers procuring in Poland, the practical question is whether the Polish supplier can issue KSeF-compliant invoices with a KSeF number and a structured FA(2) envelope. From the Warsaw side of our network, the answer is yes. Cross-border re-invoicing through Portugal under EU reverse-charge rules follows the same pattern as the Italy case.
The Spain angle: FACe and SII
Spain operates two complementary systems. FACe (Punto General de Entrada de Facturas Electrónicas) is the B2G platform for invoices to public-sector bodies, Facturae format, mandatory for all invoices to central, regional and local government. SII (Suministro Inmediato de Información) is the real-time VAT submission to the AEAT, mandatory for large companies (turnover above €6M) and voluntary for others, with a 4-day submission window from invoice issuance or receipt.
For Portugal-based buyers procuring in Spain, the practical question is whether the Spanish supplier can issue Facturae-format invoices for B2G and SII-format records for real-time VAT submission. From the Madrid and Barcelona sides of our network, the answer is yes. The Spanish invoice is re-invoiced through Portugal under EU reverse-charge rules with IVA 23% documented in the Portuguese buyer's AT return.
What ViDA changes from 2026 onward
The EU's VAT in the Digital Age (ViDA) initiative is the long-arc harmonisation programme. Key changes for merch procurement: mandatory e-invoicing for cross-border B2B (currently optional in most member states), a single EU VAT registration for cross-border sellers above a threshold, and real-time digital reporting. The timeline is 2026–2030 with phased application.
For a Portuguese buyer operating cross-border with Italy, Spain and Poland, the practical implication is that the four-system mess is on a path to convergence. Until then, suppliers who issue compliant invoices in all four systems (the Lisbon hub and its network do) save the buyer significant AP and compliance work.
FAQ
Can you invoice me in Portugal via Portal das Finanças (AT)?
Yes — native compliant e-invoices via Portal das facturas (AT) with IVA 23% are issued the day of delivery, with ATCUD and QR verification.
What if my group has entities in Italy, Spain or Poland too?
We handle that — one master service agreement, four locally-compliant invoice streams, single point of contact.
How long do you archive invoices?
10 years across all four jurisdictions, in line with EU and local fiscal law. Copies available on request within one working day.
Is Corp-Merch.PT an official partner of AT, Agenzia Entrate, AEAT or KAS?
No. We are not an official supplier, sponsor, or partner of any tax authority. We work with each tax authority on a commercial and regulatory-compliance basis.