Onboard clients onto Peppol: a playbook for Belgian accountants

This playbook is for accounting firms, bookkeepers and tax advisers who bring a portfolio of Belgian clients onto Peppol. It gives one routine per client: decide what the law requires of that client, settle the mandate and access, set up or confirm the registration, prove it with real invoices, and record who is responsible afterwards. The steps use OrdoGrid; the scope rules and mandate questions apply whatever software a client uses.

Screen-by-screen detail is in Set up Peppol in OrdoGrid; groups and VAT units are in Peppol for Belgian groups. Peppol screens and several other OrdoGrid labels (such as Profil entreprise and Changer d'entreprise) stay French in every interface language; translations are in brackets.

What the law requires of each client

The obligation has applied since 1 January 2026. A taxable person established in Belgium must issue a structured electronic invoice, or have one issued in its name, for supplies to a taxable person established in Belgium that must give its Belgian VAT number. It must also be able to receive one, itself or through a third party acting for it (art. 53 §2bis VAT Code, inserted by the Law of 6 February 2024). The default format and channel are Peppol BIS over the Peppol network (art. 13ter Royal Decree no. 1).

The duty stays with the client. Your firm can be the third party that receives or issues, but the obligation and the fine remain the client's. Lacking the technical means to issue and receive is fined €1,500 for a first infringement, €3,000 for a second and €5,000 for each further one; an infringement counts as a second or further one only if it is established at least three months after the previous fined one (Royal Decree of 8 July 2025). The general tolerance ended on 31 March 2026 and the self-billing one on 30 June 2026; FPS Finance now waives fines only exceptionally (notice of 7 April 2026).

There is a fallback, not an exemption. If a customer cannot technically receive, the supplier still issues a paper or PDF invoice, and the customer remains in breach of its own receiving duty (art. 53 §2bis, sixth paragraph, added by the Law of 10 February 2026).

Scope by client type

Source: FPS Finance, who must use e-invoicing (French). Consumer and cross-border invoices are outside the 2026 obligation (the Belgian obligation). Where a status is unclear (establishment, mixed activity, bankruptcy), settle it in your tax file first and write the conclusion down.

Settle the mandate and access before you click anything

Peppol onboarding involves two acts a general engagement letter rarely covers: someone declares to a Peppol provider that they may act for the client, and someone controls where the client's invoices arrive. Agree both in writing.

Who signs the Peppol authorisation

Sending from OrdoGrid needs an Autorisation Peppol (Peppol authorisation) for the client's VAT number. The person named under Nom complet du signataire (signatory's full name) declares being authorised to send on behalf of the company; if the client is not yet on Peppol, also to register and receive. OrdoGrid records the typed name, the user account, the VAT number and the date; it is not a qualified electronic signature.

We know of no legal rule on who must sign. We recommend that the sole trader or a director signs from their own OrdoGrid account, or that you sign under a written mandate covering Peppol registration, sending and receiving in the client's name. The name field is prefilled with the logged-in user and can be edited: never type the name of the client's director or sole trader while signed in as yourself, because OrdoGrid records your account as the signer.

Who controls the OrdoGrid company

Accept an invitation under Pending invitations in the profile menu, then move between clients with Changer d'entreprise (switch company). Every document, Peppol authorisation and API key belongs to one company.

Mandate checklist

1. Entity, enterprise number and scope decision.
2. Who signs the Autorisation Peppol, and your mandate if it is you.
3. Who is Owner and who is Administrator in OrdoGrid.
4. Who may activate, keep or release reception, and change provider.
5. Who watches the inbox, and the deputy.
6. Who may issue invoices and credit notes in the client's name.
7. Who creates and holds API keys, if an integration is used.

Triage each client by registration status

On lookup.peppol.org, the tool FPS Finance points to, enter 0208: followed by the ten-digit enterprise number, for example 0208:0123456749. If nothing is found, also try 9925:BE plus the number (for example 9925:BE0123456749): some participants are still registered only under their VAT number. The result shows whether the client can receive, not whether it can send. Also ask whether a bank, accounting package or former invoicing tool registered the client.

Peppol participant ID

A Belgian business's address on Peppol: scheme 0208, a colon and its ten-digit enterprise number. The Belgian Peppol Authority requires every Belgian participant to be identified at least this way; the VAT number (scheme 9925) may be added, not substituted.

OrdoGrid connects to Peppol through a certified access point and does not support Peppol migration keys. Each participant ID is registered with one and only one SMP (SML specification, §2.1), so a forgotten registration blocks a new one rather than splitting deliveries. Provider moves: switch Peppol access point.

The routine per client in OrdoGrid

1. Get access. The client invites you as Administrator under Team (Invite a member). Accept under Pending invitations and select the client with Changer d'entreprise.
2. Check the company data in Profil entreprise: legal name as in the KBO/BCE, address, VAT number starting with BE.
3. Have the authorisation signed. Opening Peppol leads to Autorisation Peppol until the VAT number is authorised. The signatory fills in Nom complet du signataire, ticks the box and clicks Signer et confirmer l'autorisation (sign and confirm the authorisation). Screenshot the Déclaration d'autorisation (authorisation statement) first: the Statut tab later shows signer and date, not the text.
4. Choose reception on Réception Peppol, following the triage table.
5. Check the Statut tab. Réception (Inbox) shows Enregistré (registered), or the banner shows Mode : Envoi seul (send-only); Identifiant Peppol shows the ID and Access point de réception (when shown) who receives: Notre access point (our access point) or Autre prestataire (other provider); Autorisations (n) shows "Signé par …". Repeat the lookup.
6. Prove reception, then sending, with real invoices (next section).
7. Name the inbox watcher. Owners and administrators get an email such as "[Peppol] 2 new documents received"; decide whose mailbox acts on it.
8. Update the portfolio tracker and file the evidence.

Prove it with real invoices: there is no test mode

OrdoGrid has no Peppol test or sandbox mode, and an invoice sent on Peppol is a real invoice with a real number. Never send a "test invoice" to an arbitrary participant: it would need a credit note. Prove the setup with documents that had to be issued anyway.

Reception. Your own fee invoice to the client is the simplest proof: as a Belgian VAT-registered supplier you must send it as a structured invoice anyway. Send it to the client's 0208: ID and check that it appears in the client's Inbox with NOUVEAU (new). Select the row and download it: the ZIP holds an xml/ and a pdf/ folder. For a send-only client, the invoice reaches the other provider: ask the person who watches that inbox to confirm receipt in writing, and file the confirmation.

Sending. Use the client's next real invoice to a Belgian business customer on Peppol. Envoyer opens the send popover; when the customer is found on the network, Envoi électronique via Peppol is ticked automatically, and Sauvegarder & Envoyer (save and send) sends it. In Peppol → Outbox the status should reach Traité: network delivery is complete, which is neither acceptance nor payment.

Receivables. If the client records payments in OrdoGrid, record the first one with Record payment in the invoice's Settlement panel and check Outstanding.

Worked example: Fiduciaire Lambert onboards four clients

Fiduciaire Lambert SRL, an accounting firm in Namur, onboards four clients in early October 2026.

Menuiserie Dubois in detail.

1. Duplicate found. A junior had created a company for the client from the firm's login and signed the authorisation there. Its Réception Peppol page shows Déjà présent sur Peppol via notre access point, and Activer la réception returns Réception déjà liée sur la plateforme, naming "Menuiserie Dubois": Marc Dubois activated reception in his own OrdoGrid company in 2025.
2. Access fixed. Mr Dubois, the Owner, invites the firm as Administrator. His Statut tab shows Enregistré and "Signé par Marc Dubois".
3. Reception proven. On 2 October 2026 the firm sends its third-quarter fee invoice FL-2026-0311 to 0208:0123456749: €650.00 excluding VAT plus €136.50 VAT at 21%, total €786.50. It appears in the Inbox; the ZIP goes to the file.
4. Sending proven. On 5 October Dubois invoices Cuisines Mertens SRL, a kitchen retailer on Peppol, for an oak worktop supplied without installation. F-2026-0042: €1,000.00 excluding VAT, VAT at 21% €210.00, total €1,210.00, due 4 November 2026. Envoi électronique via Peppol is ticked automatically; the accountant unticks Email, and the Outbox shows Traité the same morning.
5. Receivables checked. On 9 October Mertens pays €400.00. After Record payment (Method: Bank transfer), Settlement shows Invoice total €1,210.00, Payments (including prepayments) €400.00 and Outstanding €810.00; the invoice shows Partiellement payée (partly paid).
6. File closed. Mandate letter signed on 1 October (the firm checks the inbox every Tuesday and Friday; deputy: the client's office), dated lookup, Statut screenshot, both proofs, next review 1 April 2027.

For Studio Lenoir, the firm checks that invoices to business customers carry the mention required since 2025, "Régime particulier de la franchise de taxe": OrdoGrid's Régime de la franchise de taxe option prints it on French documents and the Dutch wording on Dutch ones, but only a translation on English or German documents, so the firm checks that the company's Langue des documents (document language) is French or Dutch (small business exemption invoicing).

Run the portfolio

Tracker columns

Move every client through the same stages: scope decided, access and mandate in place, registered, reception proven, sending proven, handed over or managed. Count clients per stage each week: an in-scope client for whom nobody yet receives under 0208 is exposed to the fine; "reception proven" is your evidence that it no longer is.

When to triage a client again

• Its VAT status changes: franchise entry or exit (threshold €25,000 in 2026, €26,000 from 2027 under the Law of 23 September 2026), taxed supplies added to art. 44-exempt ones, or the end of the flat-rate regime.
• Its enterprise number, legal form or VAT number changes; after a VAT number change, OrdoGrid shows Nouveau numéro de TVA détecté and needs a new signature.
• It changes bank, accounting package or invoicing tool, any of which may register it elsewhere.
• A supplier reports failed delivery, or invoices still arrive by email.
• The planned e-reporting law is adopted (see the FAQ and e-reporting 2028).

Integrations: one API key per client company

Each OrdoGrid API key acts for one company only. An owner or administrator of the client company creates it under API keys (Create key, Name, Permissions, Expires on); the secret appears once (Copy this key now). Start with GET /api/v1/me, which confirms the company the key acts for. Your firm login is not an API credential, and there is no sandbox: calls act on real data and the real network (public API integration).

Managed inbox or client handover

Whatever the model, the watcher must know three actions:

1. A misaddressed invoice is not booked: FPS Finance advises rejecting it, for example with Répondre (reply) → RE Rejetée (rejected) and a reason code.
2. An outbound invoice still without Traité after one working day is checked with Vérifier, then reported to OrdoGrid support with its number. It is not sent again by another route: OrdoGrid itself blocks resending while the outcome is uncertain.
3. A customer not on Peppol gets a PDF by email under the fallback, and no structured copy later (client not on Peppol).

OrdoGrid has no purchase ledger or approval workflow: received invoices are viewed, downloaded and answered there, and booked in your accounting software. Where the client's plan includes Accounting, its export offers Export format presets for Winbooks and Exact Online (CSV layouts, not a direct link). On the Business plan, the client can also send you a share link from Accounting (Create share link): for 30 days it opens a read-only page where you download a ZIP with the period's transactions, their supporting documents and the imported bank statements, without an OrdoGrid account; anyone holding the link can do the same. Only owners and administrators can create such a link, and they can withdraw it at any time with Revoke under Share links for your accountant. Period files: prepare a handover for your accountant.

Edge cases and common mistakes

Evidence to keep

What the law requires. Invoices sent and received are kept for seven years from 1 January of the year after their date (art. 60 VAT Code, as amended by the Law of 18 December 2025); 15 or 25 years for some invoices linked to the revision of VAT deduction on immovable property. OrdoGrid is not a legal archive.

What we recommend per client:

1. The signed mandate or engagement letter covering Peppol.
2. The scope decision with its basis, including "no obligation" decisions.
3. Dated lookup.peppol.org results, before and after setup.
4. Screenshots of the Déclaration d'autorisation before signing and of the Statut tab after.
5. For send-only clients, the receiving provider's written confirmation.
6. The ZIP of the first inbound invoice, the XML of the first outbound one and its Traité date.
7. For each fallback, the popover reason Le client n'est pas enregistré sur le réseau Peppol (customer not registered) or a dated lookup.
8. A monthly ZIP of Inbox and Outbox in the client's own storage.

FAQ

Can I sign the Peppol authorisation for my client?

Only if the client has authorised you to. The declaration states that the signatory may act for the company, and OrdoGrid records your account as the signer. We recommend the sole trader or a director signs, or you sign under a written mandate kept in the file.

Is send-only enough for a client?

Yes, if another provider already receives for the client's 0208 ID and someone watches that inbox. If nobody receives, the client lacks the means to receive, which is what the €1,500 fine targets.

Do clients under the small business exemption need Peppol?

Yes. FPS Finance states that the obligation applies to franchise taxpayers: they must receive structured invoices and issue them to VAT-registered business customers established in Belgium. Only businesses making exclusively art. 44-exempt supplies and businesses not established in Belgium are outside both duties.

Can one Peppol inbox serve all my clients?

No. Each client is registered under its own enterprise number, and only one provider receives for an ID. In OrdoGrid each client company has its own inbox; as Administrator you get each company's notification emails and switch with Changer d'entreprise.

How do I test a client's setup without a test mode?

With real documents: your own fee invoice to the client proves reception, and the client's next invoice to a customer on Peppol proves sending. Never send a test invoice to an arbitrary participant.

What if my client's customer is not on Peppol?

The client issues a PDF or paper invoice under the legal fallback, keeps evidence that the customer was not reachable, and does not resend it on Peppol later. The customer remains in breach of its own receiving duty.

Can the client deduct Peppol software costs at 120%?

Small companies and self-employed natural persons can deduct 120% of invoicing software costs, excluding depreciation, used to issue, send and receive structured invoices, for taxable periods 2024 to 2027 (Law of 6 February 2024). Check the FPS Finance guidance before including other costs, such as implementation advice.

Does e-reporting change this onboarding?

Not yet. On 18 July 2026 the Council of Ministers approved a preliminary draft law for near-real-time reporting of invoice data by supplier and customer, but it is not law, the official release gives no start date, and no invoice data is sent to the administration today. If, as commentators report, e-reporting builds on the Peppol network, a clean 0208 registration and a watched inbox will be the starting point.