Hermes — the Brussels-Capital B2G gateway

Hermes is the regional e-invoicing platform of Brussels-Capital. Operated by Talan Belgium for Bruxelles Economie et Emploi, it reproduces for Brussels public bodies the PEPPOL-BIS 3.0 architecture deployed by Mercurius at federal level, and integrates by right with the European PEPPOL network.

Genesis: 2018 Brussels Ordinance

The Brussels-Capital Region, like other Belgian federated entities, must transpose Directive 2014/55/EU on e-invoicing in public procurement. It does so by the Ordinance of 17 May 2018 on public procurement, completed by the Implementing Order of the Brussels-Capital Government of 18 July 2019.

• May 2018 — Ordinance. Inserted in art. 7bis: "The contracting authorities referred to in art. 2 must be able to receive and process structured electronic invoices compliant with the EN 16931 standard published in the Official Journal of the European Union".
• July 2019 — Implementing Order. Designates Hermes as the official platform. Talan Belgium wins the design-build contract (tender 2018/S 213-487092).
• January 2020 — MVP in production. First connected body: Bruxelles Economie et Emploi.
• October 2020 — PEPPOL-BIS 3.0 switch. Hermes adopts the PEPPOL Billing profile to align with Mercurius. The proprietary UBL 2.0 format is deactivated.
• 2021-2023 — Extension to para-regional bodies. Seven main bodies (STIB, Actiris, Bruxelles-Proprete, Bruxelles-Mobilite, Brussels Environment, IBSA, Visit.brussels) are connected in cohort.
• 2024 — Contract renewal. Talan wins the five-year renewal of the Hermes contract (regional public procurement RBC-2023-13).

Governance: BEE + Talan

Hermes governance is two-headed:

• Bruxelles Economie et Emploi (BEE) — service of the Brussels Regional Public Service (SPRB), political and budgetary authority. Defines the roadmap, terms of use and the scope of connected entities.
• Talan Belgium — technical operator. Consulting and integration firm (Talan Group, ~6,000 employees, Paris/Geneva/Brussels), specialised in e-government platforms. Operates the infrastructure from two Tier III datacenters in Anderlecht and Diegem.
• OpenPEPPOL Authority: Hermes is certified PEPPOL AP; annual audits (Talan SCA / OpenPEPPOL report) are forwarded to BEE.
• Steering committee: quarterly, gathers BEE, Talan, BOSA (inter-level consistency) and the main connected bodies.

Hermes architecture

┌─────────────────────────────────────────────────────────────────────┐
│                  Hermes architecture - logical view                 │
├─────────────────────────────────────────────────────────────────────┤
│                                                                     │
│   Supplier                                                          │
│       │                                                             │
│       │ UBL 2.1 PEPPOL-BIS 3.0                                      │
│       ▼                                                             │
│   PEPPOL AP (Belfius, Unifiedpost, etc.) ─── AS4 ──┐                │
│                                                    │                │
│                                                    ▼                │
│   ┌─────────────────────────────────────────────────────┐           │
│   │  Hermes Network - PEPPOL AP Brussels-Capital Region │           │
│   │  (Talan Belgium - 2 Tier-III datacenters)           │           │
│   └─────────────────────┬───────────────────────────────┘           │
│                         │                                           │
│       ┌─────────────────┼──────────────────┬─────────────┐          │
│       ▼                 ▼                  ▼             ▼          │
│  Bruxelles-     Bruxelles-Mobilite    STIB / MIVB    Actiris        │
│  Proprete        (Iris²)              (transport)    (employment)   │
│                                                                     │
└─────────────────────────────────────────────────────────────────────┘

Hermes plays three technical roles:

• PEPPOL Access Point (AP) — AS4 endpoint. Compliant with the eDelivery CEF profile, identified by the URL https://ap.hermes.brussels/as4.
• Regional SMP (Service Metadata Publisher): publishes the endpoints of para-regional bodies so that a foreign or Belgian sender AP can route them via PEPPOL SML.
• Internal integration workflow: UBL conversion to the bodies' ERPs (SAP S/4HANA for STIB, Workday for Actiris, Oracle Financials for Bruxelles-Proprete), status tracking, 10-year legal archiving (BCE + territorial Court of Auditors).

Connected bodies

The full list of 38 connected entities (Brussels CPAS, 19 municipalities, intermunicipal entities Iris²/Bruxelles-Foret/IGEAN) is accessible in the Hermes SMP via PEPPOL SML.

Integration with Mercurius via PEPPOL

Hermes and Mercurius are two distinct PEPPOL APs, but they interoperate automatically because they share the same PEPPOL network. A supplier goes through a single sender AP (their own, or their ERP provider), which resolves the recipient via SML/SMP:

1. The supplier issues the UBL 2.1 invoice to their sender AP (e.g. Unifiedpost).
2. The sender AP fires a PEPPOL SML DNS query: B-<hash(BCE)>.iso6523-actorid-upis.edelivery.tech.ec.europa.eu.
3. The SML returns the URL of the responsible SMP (Hermes or Mercurius depending on the target body).
4. The sender AP reads the SMP to obtain the recipient's AS4 endpoint and the list of accepted document types.
5. The invoice is delivered via AS4 to Hermes (or Mercurius), which integrates it into its regional workflow.

This mechanism means that a given Belgian supplier never needs to "know" Hermes or Mercurius: they push their UBL into PEPPOL and the resolution is automatic.

2024 volumes

• Total volume: 451,000 B2G invoices in 2024 (+12% vs 2023, source BEE report).
• Top 3 bodies by volume: STIB (185,000 invoices/year), Bruxelles-Proprete (62,000), Actiris (48,000).
• Rejection rate: 1.8% (mainly invalid recipient BCE or CIUS Belgium Schematron failure).
• Average payment turnaround: 38 calendar days (versus 52 days in former paper flow).
• Top 5 sender APs: Belfius (24%), Unifiedpost (18%), Cegeka (12%), Combell (9%), e-Connect (7%).

Cross-links

• Belgium hub — full e-invoicing mandate
• Mercurius — federal B2G platform
• PEPPOL-BIS 3.0 Belgium — technical spec
• BCE/KBO — ICD 0208 identifier
• PEPPOL access points in Belgium
• Royal Decree of 20 March 2025 — B2B extension
• Bruxelles Economie et Emploi — Hermes page
• Talan Belgium — technical operator
• OpenPEPPOL — Authorities list