What is a Peppol ID, and how do I find a customer's?
Learn what a Peppol participant identifier is, how the Directory and SMP route documents to it, how to look one up, and what to do when a customer isn't listed.
You have agreed to send a customer their invoices over Peppol. Before you can, you need to know where to send them — and on Peppol, "where" is not an email address or a company name. It is a participant identifier, the address the whole network routes on. Getting comfortable with it removes most of the mystery from Peppol, because almost everything else is machinery built around this one piece of data.
What a participant identifier actually is
A Peppol ID has two parts: a scheme and a value. The scheme says what kind of number the value is; the value is the number itself. In practice the value is usually a tax or company registration number the business already has — a VAT number or a national enterprise number — and sometimes a GLN, a global location number used more in retail and logistics.
The scheme matters because the same digits can mean different things in different registries. A Belgian company might be addressed by its enterprise number under one scheme or its VAT number under another, and each has its own scheme code. Written out, an identifier looks like a scheme code followed by the value — the code tells any access point which register to interpret the number against. You rarely type this by hand, but it explains why "just the VAT number" is sometimes not enough on its own: the scheme has to travel with it.
How the ID turns into a delivery
An identifier is only useful if the network can find who is responsible for it. Two components do that job.
The SML — the Service Metadata Locator — is the network's directory layer, built on DNS. Given a participant identifier, it points to the SMP (Service Metadata Publisher) that holds that participant's details. The SMP is the record that says two things: which access point delivers documents for this participant, and which document types they accept — a BIS Billing 3.0 invoice, a credit note, and so on.
So when you send, your access point takes the recipient's identifier, uses the SML to find their SMP, reads the SMP to learn where to deliver and whether the recipient accepts that document type, and routes it there. This is the plumbing behind the four-corner model. If that model is still fuzzy, what is Peppol lays it out from the top.
The point worth holding on to: a company can have a VAT number and still not be reachable on Peppol, because reachability depends on that SMP record existing, not on the number existing.
Looking one up
The human-facing tool is the Peppol Directory, a public, searchable index of registered participants. You can search it by company name or by identifier, and if a business appears there with the invoice document type listed, they are reachable.
Two habits make the Directory more reliable. Search by the exact identifier rather than the name where you can — the descriptive listing is opt-in, so a participant can be reachable on the network without being easy to find by name. And treat a hit as answering "can I reach them", not "will this exact invoice pass every rule" — the second depends on the document itself, not on registration. Checking a customer on the Peppol network goes deeper on doing this well before you commit to a delivery date.
When the customer isn't listed
Sometimes the answer is that they are not on the network. That is their gap to close, not yours: you cannot register a customer as a Peppol participant on their behalf, and no sending tool can either. What you can do is tell them plainly what to do — register through an access point or service provider, often the same accounting software they already run — after which they will have their own identifier and SMP record and become reachable. Until then, you fall back to a PDF by email for that one customer. Ask early, because registration runs on their timeline.
Where this fits if you send from Stripe
If you bill through Stripe, you do not run the SML and SMP lookups yourself. When you start a send in Peppost, it resolves the recipient's identifier against the Peppol Directory and confirms they accept the document — and it does this before any credit is spent, so a customer who is not on the network is reported back without charging you. That check is part of the normal send rather than a separate chore; the sending guide shows where it sits in the flow, and the FAQ covers what the lookup does and does not promise.