B2G mandate — e-invoicing via accredited providers

When a Greek business invoices the state or a local authority (a B2G relationship, business-to-government), it must now issue a structured electronic invoice — no longer a PDF. Greece chose a distinctive model: the invoice goes through an accredited service provider (paroxos ilektronikis timologisis) that seals it, transmits it to the administration over PEPPOL, and reports the summary to myDATA. Rolled out in tiers since 2023-2024.

History — from 2014/55/EU to the phased mandate

Directive 2014/55/EU requires all EU contracting authorities to be able to receive and process electronic invoices compliant with the EN 16931 standard. Greece, like every member state, had to transpose. But rather than imposing a single public deposit platform (the French Chorus Pro model), it built on its myDATA infrastructure and on an ecosystem of accredited providers already mobilised for tax transmission.

2014       | Directive 2014/55/EU: mandatory e-invoicing at receipt for all
           | EU contracting authorities. Greece, like other member states,
           | must transpose.
           |
2019-2020  | Greece rolls out myDATA and builds the public-sector receiving
           | infrastructure. Slow transposition while the public sector's
           | digital capacity is built up.
           |
2022       | Law 4972/2022 and implementing texts: framework for mandatory B2G
           | e-invoicing. Choice of a provider-based model (paroxoi ilektronikis
           | timologisis), distinct from an all-in-one state platform.
           |
2023       | Decision A.1035/2023 and follow-ups: B2G obligation starts in tiers.
           | First categories of public spending covered. EN 16931-aligned
           | format, PEPPOL transport.
           |
2024       | Progressive widening: more public bodies and procurement categories
           | required to receive and process e-invoices via accredited providers.
           | Systematic myDATA linkage.
           |
2025-2026  | B2G generalisation + transition to the B2B mandate (EU derogation).
           | Accredited providers become the common backbone for B2G and B2B
           | flows.

Governance — AADE + GSIS + ministries

The scheme is jointly run. AADE (the Independent Authority for Public Revenue) accredits the service providers and operates myDATA. GSIS (the General Secretariat for Information Systems of Public Administration), under the Ministry of Digital Governance, operates the public-sector receiving infrastructure and the national PEPPOL access point. The Ministry of Finance co-signs the A. decisions.

This split explains the dual recipient: one B2G invoice must satisfy both the procurement obligation (EN 16931 receipt by the body) AND the tax obligation (transmission to myDATA). The accredited provider bridges the two.

Schema — providers, PEPPOL, myDATA

The flow starts at the business, passes through an accredited provider, and splits toward the administration (B2G / PEPPOL channel) and toward AADE (myDATA):

Supplier (business)
        |
        |  EN 16931 invoice (UBL / national profile)
        v
+---------------------------+
|  Accredited e-invoicing   |   accredited service provider
|  provider (paroxos)       |   - signs / seals the invoice
+---------------------------+   - transmits to the administration
        |                       - transmits the summary to myDATA (AADE)
        |  PEPPOL BIS / B2G channel
        v
+---------------------------+        +-------------------------+
|  Contracting authority    |        |  AADE — myDATA          |
|  (public body)            |        |  (electronic books)     |
+---------------------------+        +-------------------------+
        |                                       ^
        |  acceptance / rejection               |  MARK + classification
        v                                       |
   Commitment / payment  --------------------- +

Note: the accredited provider acts as a PEPPOL access point AND a
bridge to myDATA — one flow, two recipients.

• Accredited provider — entity approved by AADE to issue, seal, transmit and archive electronic invoices.
• PEPPOL access point — the Greek administration is reachable on the PEPPOL network; providers deposit B2G invoices there.
• National CIUS — Greek usage specification of the EN 16931 core (AFM codes, myDATA classification).
• myDATA reporting — summary transmitted to AADE, MARK returned, sealing into the electronic books.

Greek B2G vs other EU mandates

Adoption — phased timeline

• 2023: B2G obligation starts on the first categories of public spending (A.1035/2023 and related texts).
• 2024: widening to more public bodies and procurement types; generalised EN 16931 receipt by the administration.
• 2025-2026: near-complete B2G coverage and continuity with the B2B mandate — accredited providers serve both flows.
• myDATA effect: the state already holds the data via the electronic books, making B2G receipt easier to control.

Common pitfalls

• Assuming a PDF is enough to invoice the state. For covered bodies, only a structured EN 16931 invoice via accredited provider / PEPPOL is acceptable. The PDF is rejected.
• Choosing a provider not accredited by AADE. Only the paroxoi on the AADE registry can seal and report to myDATA. Verify accreditation before contracting.
• Forgetting the dual obligation. A B2G invoice must be both received by the body (procurement) AND transmitted to myDATA (tax). Covering one without the other leaves a non-compliance.
• Wrong public-buyer addressing. The recipient body must be correctly addressed on PEPPOL (AFM + unit code); a wrong address blocks the commitment.
• Ignoring the national CIUS. The EN 16931 core is not enough: Greek-specific codes (myDATA classification, AFM) must be present.

Cross-links

• Greece hub — full view
• myDATA — electronic books
• B2B mandate 2025-2026
• Accredited provider model
• AFM + GEMI — identifiers
• ViDA 2030 — DRR alignment
• AADE — e-invoicing
• GSIS — public information systems