EN 16931 and the Peppol Network: The Digital Backbone of Cross-Border E-Invoicing

In short: EU public buyers must accept invoices that conform to EN 16931; whether a supplier may use another format is for the law of the buyer’s state, and several states have made e-invoicing mandatory in public procurement. Before signing, check whether the buyer supports Peppol and has a registered Peppol ID, whether the supplier has a certified Access Point connection, and which fields EN 16931 requires. The contract itself should specify the invoice format, transmission method, party identifiers and the consequences of non-compliance for payment.

If your invoice does not conform to EN 16931 or is not transmitted via Peppol, and the buyer’s state has made e-invoicing mandatory, an EU public buyer may refuse it — and in B2B contracts, a well-advised counterparty may use non-compliance as a ground to delay or withhold payment. This is not a technical inconvenience — it is a contractual and legal risk.

For companies supplying goods or services to EU public buyers, or engaging in cross-border B2B transactions with European partners, compliance with EN 16931 and the Peppol network is increasingly material to contract performance and payment. Understanding how these standards interact with cross-border contract structuring is essential for managing legal exposure.

EN 16931 is a technical standard developed by the European Committee for Standardization (CEN) on behalf of the European Commission, implementing Directive 2014/55/EU. It defines the semantic data model for the electronic invoice — the required fields, structure, and data types that an invoice must include to be legally valid and machine-readable across EU member states.

The standard specifies:

• required data fields: invoice number, issue date, seller and buyer identifiers, VAT details, and payment terms;
• XML encoding in one of the two syntaxes: UBL 2.1 (Universal Business Language) or UN/CEFACT CII;
• support for references to contract documents, purchase orders, and delivery confirmations;
• alignment with the eIDAS Regulation (EU) No 910/2014, ensuring authenticity and long-term archiving.

Since April 2019 (April 2020 for sub-central authorities), public sector buyers in the EU have been required to accept invoices compliant with EN 16931. The standard is also progressively adopted in the private sector (B2B).

While EN 16931 defines the invoice format, Peppol (Pan-European Public Procurement Online) provides the infrastructure to transmit these invoices securely and interoperably across borders.

Established through an EU-funded initiative and now governed by OpenPeppol, the network enables companies to:

• send and receive invoices in the EN 16931 format via certified Peppol Access Points (APs);
• use Peppol BIS (Business Interoperability Specifications) — standardized message templates;
• identify themselves through a unique Peppol ID linked to a central registry;
• verify recipient readiness using the Peppol SMP (Service Metadata Publisher).

A company connects to Peppol through a certified Access Point provider, registers, obtains a Peppol ID, and can then send or receive documents in a unified format regardless of the counterpartyʼs local software.

As of 2026, Peppol operates in over 30 countries.

Europe (B2G, with B2B expansion)

Mandatory in B2G: Germany, France, Belgium, the Netherlands, Sweden, Denmark, Norway, Finland, Austria, Estonia, Lithuania, Poland (alongside the national KSeF system). Active B2B expansion: Ireland, Italy.

Outside Europe

Singapore — the first Asian country to mandate Peppol for public procurement. Australia and New Zealand — part of their national digital economy strategy. Japan — implemented JP PINT, a Peppol-compatible standard. Canada — national integration at pilot stage.

Several countries use national e-invoicing platforms alongside or instead of Peppol.

Your EU buyer now demands EN 16931 invoices? Send us the contract — we will add the e-invoicing clause that keeps payments flowing.

If your invoice does not conform to EN 16931 or is not transmitted via Peppol, and the buyer’s state has made e-invoicing mandatory, an EU public buyer may refuse it — and in B2B contracts, a well-advised counterparty may use non-compliance as a ground to delay or withhold payment.

This is particularly material when:

• participating in EU public tenders or procurement procedures;
• supplying goods or services to large European companies with automated invoice processing;
• issuing invoices that are subject to EU VAT reporting requirements.

When structuring international contracts with Ukrainian counterparties or reviewing cross-border agreements, it is advisable to verify: whether the buyer supports Peppol and has a registered Peppol ID; whether the supplier has a certified Access Point connection; which specific fields must be populated to comply with EN 16931 for the relevant jurisdiction.

A legal due diligence of the counterparty should include verification of their Peppol registration status and EN 16931 compliance where invoicing is a material element of the transaction. Where required, our team can provide a legal opinion confirming compliance with the specific EU jurisdiction requirements.

A contract with a European buyer should explicitly address:

• the required invoice format (EN 16931 / UBL 2.1);
• the transmission method (Peppol network or applicable national platform);
• the technical identifiers of the parties (buyerʼs Peppol ID);
• the consequences of format non-compliance: whether this constitutes grounds for payment refusal or delay.

The absence of these provisions leaves the buyer with a technically defensible basis to reject the invoice — with legal consequences for the supplier.

Where the contract also contemplates electronic execution, we recommend reviewing our analysis of electronic contracts in Ukraine, which covers DocuSign, QES, and banking compliance in detail.

E-invoicing runs on structured data about counterparties and transactions. The compliance side of that data layer sits with our data protection and digital compliance practice.