Peppol BIS Billing 3.0 is the European standard for structured electronic invoice exchange. It has been mandatory for EU public procurement since 2019 (Directive 2014/55/EU), and a growing number of countries are extending the obligation to B2B. Croatia’s Fiscalisation 2.0 framework also uses Peppol BIS Billing 3.0 as its reference format.
This article explains the key building blocks of the standard — the UBL 2.1 syntax, the EN 16931 semantic norm and Peppol’s 4-corner model — and what it actually means to operate as a certified Peppol Access Point.
What „Peppol BIS Billing 3.0“ really means
The name is a stack of three layers. „Peppol“ is the network (Pan-European Public Procurement OnLine), governed by OpenPeppol AISBL in Brussels. „BIS“ stands for Business Interoperability Specification — an implementation guideline that pins down how Peppol is used for a specific use case. „Billing 3.0“ is the current version of the invoicing specification.
Technically, BIS Billing 3.0 mandates the UBL 2.1 syntax (Universal Business Language, an OASIS standard) and compliance with European norm EN 16931, which defines the semantic model of an invoice — which fields must be present, which are conditional and how taxes are calculated.
UBL 2.1 and EN 16931 — syntax and semantics
UBL 2.1 provides the XML „skeleton“ of the message. It specifies tags (cbc:ID, cac:AccountingSupplierParty, cbc:PayableAmount) and the document structure. Without UBL, there is no shared way for European ERPs to read the same document.
EN 16931 goes one step further and prescribes semantics: which UBL elements are mandatory, which values are allowed (e.g. tax category code lists) and how totals are calculated. A validator (such as the public Peppol validator) checks compliance with EN 16931 — not just the XML schema.
Practical consequence: your ERP can „export UBL“ and still fail EN 16931 validation if, for example, it omits the tax category code or miscalculates VAT.
The 4-corner model
Peppol’s core concept is the 4-corner model. The sender (C1) sends a document through their Access Point (C2). That AP hands it over the Peppol network to the receiving AP (C3), which delivers it to the receiver (C4). Crucially, sender and receiver do not need to share an Access Point — like email, the network connects them.
Addressing uses Peppol Participant IDs (e.g. „9934:HR12345678901“, where 9934 is the ISO scheme for the Croatian tax ID). The Service Metadata Publisher (SMP) and Service Metadata Locator (SML) are DNS-like services that tell your AP where the receiver’s AP lives.
What a certified Peppol Access Point actually does
- Holds formal certification from OpenPeppol AISBL and the national Peppol Authority — REDOK has passed the audit for Croatia.
- Technical commitments: AS4 protocol with signing and encryption, validation of every message on both ingress and egress.
- Network SLA: 99.5 %+ uptime, exchange logs retained for 11+ years for audit.
- Operational duty to report incidents to other Access Points and to the Peppol Authority.
What this means in practice for you
If your company sends invoices to a customer in Germany, Norway or Singapore — all Peppol member jurisdictions — it is enough that you send through REDOK. We take care of matching the local BIS, of validation and of routing through the right Access Point. From your side, that is one contract, one integration and one SLA.
If e-invoicing is new territory for you — whether driven by Fiscalisation 2.0 or by expansion into the EU — get in touch. The REDOK team runs a free compatibility check of your ERP against Peppol BIS Billing 3.0 and gives concrete next-step recommendations.