B2G invoicing — FE-AP, eSPap and CIUS-PT

When a company invoices the Portuguese state (a ministry, a public hospital, a town council), it must send a structured electronic invoice through the FE-AP system (Faturação Eletrónica na Administração Pública). Operated by eSPap (the state's central purchasing and shared-services entity), it transposes EU Directive 2014/55/EU and relies on the national CIUS-PT profile, compliant with the EN 16931 standard.

History — from Directive 2014/55 to roll-out

Directive 2014/55/EU requires all EU administrations to be able to receive electronic invoices compliant with the EN 16931 standard. Portugal transposes it via Decreto-Lei n.º 123/2018, which creates FE-AP and designates eSPap as operator of the central access point.

On the supplier side, roll-out was phased and saw many COVID-19 postponements: obligation for large companies from 1 January 2021, then gradual extension to micro, small and medium enterprises, with a final deadline pushed to 2025. During the transitional period PDF was tolerated; it gives way to the structured CIUS-PT format.

2014       | Directive 2014/55/EU — mandates B2G e-invoicing across the EU
           | and founds the future EN 16931 standard.
           |
2017       | Decreto-Lei n.º 111-B/2017 — overhaul of the Código dos
           | Contratos Públicos (CCP), prepares procurement digitisation.
           |
2018       | Decreto-Lei n.º 123/2018 — transposes the directive: FE-AP
           | (Faturação Eletrónica na Administração Pública) becomes the
           | mandatory framework; eSPap is designated operator.
           |
2020       | FE-AP central access point + FE-AP Web go live. Obligation
           | effective for central government (purchasing entities).
           |
2021       | Obligation for LARGE supplier companies (from 1 January 2021,
           | after COVID postponements).
           |
2022-2024  | Gradual extension to SMEs; multiple successive postponements
           | of the transitional PDF regime (tolerated) toward mandatory
           | structured invoicing.
           |
2025       | Obligation deadline for MICRO, SMALL and MEDIUM suppliers to
           | the administration (after a final postponement). Convergence
           | toward EN 16931 / CIUS-PT.

Governance — eSPap and FE-AP

eSPap (Entidade de Serviços Partilhados da Administração Pública) is the Portuguese state's central purchasing and shared-services entity. It operates the FE-AP central access point that receives, validates and distributes invoices to purchasing public entities, plus FE-AP Web, a manual-entry portal for suppliers without an integrated solution.

Public entities are identified by their NIF (often a 6xx prefix for the public sector) and, for routing, by an access-point identifier. Portugal also accepts reception over the PEPPOL network (eDelivery AS4), with eSPap acting as access point.

Technical schema — CIUS-PT, UBL 2.1, CII

The reference format is the EN 16931 standard, profiled for Portugal by CIUS-PT (Core Invoice Usage Specification — Portugal). Two XML syntaxes are allowed: UBL 2.1 (OASIS) and UN/CEFACT CII. CIUS-PT notably mandates carrying the ATCUD and consistency with Portuguese VAT rules.

<?xml version="1.0" encoding="UTF-8"?>
<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2">
  <cbc:CustomizationID>urn:cen.eu:en16931:2017#compliant#urn:feap.gov.pt:CIUS-PT:2.0.1</cbc:CustomizationID>
  <cbc:ProfileID>urn:fdc:peppol.eu:2017:poacc:billing:01:1.0</cbc:ProfileID>
  <cbc:ID>FT 2026A/00417</cbc:ID>
  <cbc:IssueDate>2026-06-12</cbc:IssueDate>
  <cbc:InvoiceTypeCode>380</cbc:InvoiceTypeCode>
  <cbc:DocumentCurrencyCode>EUR</cbc:DocumentCurrencyCode>
  <!-- ATCUD carried in a CIUS-PT additional reference -->
  <cac:AdditionalDocumentReference>
    <cbc:ID>JFHA3T7N-417</cbc:ID>
    <cbc:DocumentTypeCode>ATCUD</cbc:DocumentTypeCode>
  </cac:AdditionalDocumentReference>
  <cac:AccountingSupplierParty>
    <cac:Party>
      <cac:PartyTaxScheme>
        <cbc:CompanyID>PT509876543</cbc:CompanyID>
        <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
      </cac:PartyTaxScheme>
    </cac:Party>
  </cac:AccountingSupplierParty>
  <cac:AccountingCustomerParty>
    <cac:Party>
      <cbc:EndpointID schemeID="0237">600000123</cbc:EndpointID>
      <cac:PartyTaxScheme>
        <cbc:CompanyID>PT600000123</cbc:CompanyID>
        <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
      </cac:PartyTaxScheme>
    </cac:Party>
  </cac:AccountingCustomerParty>
  <cac:TaxTotal>
    <cbc:TaxAmount currencyID="EUR">230.00</cbc:TaxAmount>
  </cac:TaxTotal>
  <cac:LegalMonetaryTotal>
    <cbc:PayableAmount currencyID="EUR">1230.00</cbc:PayableAmount>
  </cac:LegalMonetaryTotal>
</Invoice>

B2G vs B2B in Portugal

Adoption — phased roll-out

• Central government + large companies: obligation effective since 2021. Large suppliers issue CIUS-PT to the FE-AP access point.
• SMEs and micro-enterprises: brought in through successive phases, with a final deadline pushed to 2025 after several postponements.
• FE-AP Web: very small suppliers key their invoices directly into the portal, without integrating a connector.
• PEPPOL convergence: suppliers already on PEPPOL (for other countries) can route to eSPap as access point, easing cross-border.

Common pitfalls

• Thinking FE-AP replaces SAF-T. A B2G invoice issued in CIUS-PT must also be reported to the AT via SAF-T / e-fatura. Both obligations coexist.
• Forgetting the ATCUD in CIUS-PT. The national profile requires carrying the ATCUD in a dedicated reference. A B2G invoice without ATCUD is rejected.
• Wrong CustomizationID. The profile must explicitly reference CIUS-PT (not another country's CIUS) to pass FE-AP EN 16931 validation.
• Wrong public-entity identifier. Routing depends on the buying entity's NIF/endpoint; an identifier error blocks delivery to the right service.
• Relying on PDF. PDF was only tolerated during the transitional period; for in-scope suppliers, only the structured CIUS-PT format is now valid.

Cross-links

• Portugal hub — full view
• SAF-T (PT) — tax reporting
• ATCUD + QR code
• ViDA 2030 — upcoming B2B
• NIF — tax identifier
• eSPap — Faturação Eletrónica (FE-AP)
• Diário da República — DL 123/2018 / DL 111-B/2017