Peppol May Release 2026 now mandatory: five new Dutch validation rules announced

The Hague, 19 August 2026 – As of 17 August 2026, the Peppol May Release 2026 is mandatory for all message traffic across the Peppol network. The release brings updated schematrons, revised code lists and a number of syntax changes. For the Dutch market, the most significant change is a set of five new Netherlands-specific validation rules covering organisation identifiers. Those rules are warnings for now, but will become fatal in a subsequent release.

What the Peppol May Release 2026 changes technically

OpenPeppol published the release on 20 May 2026, following a member review that opened on 2 March 2026. For e-invoicing it concerns Peppol BIS Billing 3.0 version 3.0.21. The remaining post-award specifications, including Order, Ordering, Despatch Advice, Catalogue and Invoice Response, land on version 3.0.17. Both sets became mandatory in production on 17 August 2026.

The main components of this Peppol schematron update and the accompanying Peppol validation rules 2026:

• Syntax extension in the Order. Within cac:OrderLine, the new structure cac:QuotationLineReference with the element cbc:LineID has been added, allowing an order line to reference a specific quotation line.
• Updated code lists. The EAS, ICD, ISO 4217 and UNCL7161 code lists have been refreshed, with matching changes in the Peppol BIS 3 validation artefacts.
• Danish rules turn fatal. PEPPOL-COMMON-R052 and PEPPOL-COMMON-R053, which check the Danish Chamber of Commerce number and the Danish ERSTORG number, move from warning to fatal error. Both rules were introduced as warnings in the November 2025 release.
• Billing changes. A new optional profile 02 makes the Invoice Response a mandatory process step. Organisations that want to use that profile must register for it separately in the SMP. In addition, rule BR-CO-25 has been removed, PEPPOL-EN16931-R004 has been updated, and two temporary French profiles have been added to PEPPOL-EN16931-R007.

The scope is therefore wider than the order-to-cash chain alone. Organisations that only send invoices are affected just as much, even if Peppol Despatch Advice validation is not relevant to them.

Five new Dutch Peppol validation rules

The biggest change for the Dutch and Belgian market sits in the common schematrons, where five new rules verify the structure of Dutch organisation identifiers:

• PEPPOL-COMMON-R054 checks that an identifier using scheme 0106 (Chamber of Commerce number) consists of exactly eight digits.
• PEPPOL-COMMON-R055 checks that an identifier using scheme 0190 (OIN) consists of exactly twenty digits.
• PEPPOL-COMMON-R056-1 checks that an identifier using scheme 9944 follows the format NL123456789B12.
• PEPPOL-COMMON-R056-2 applies the same format check to the Dutch VAT identifier.
• PEPPOL-COMMON-R057 checks that an identifier using scheme 0217 (Chamber of Commerce establishment number) consists of exactly twelve digits.

All five rules ship with severity warning. OpenPeppol follows a well-established pattern here: a new format check starts as a warning and is converted to a fatal error in a following release. That happened earlier with the Swedish organisation number, the Belgian enterprise number and the Australian ABN, and it is happening in this release with the two Danish rules.

Netherlands Peppol Authority published a parallel May release

On 22 May 2026, the Netherlands Peppol Authority (NPA) announced that the national validation artefacts have been updated as well. These cover SI-UBL 2 with NLCIUS version 2.0.3.13, the g-account extension version 1.0.2.13 and NLCIUS-CII version 1.0.3.13. The underlying EN 16931 validation rules were updated to version 1.3.16. These artefacts also became mandatory on 17 August 2026, putting the national and European deadlines on the same date.

What this means for Peppol Serviceproviders and software vendors

The schematron update itself is usually a matter of replacing artefacts and running regression tests. The new Dutch validation rules ask for more. R054 through R057 do not touch the software but the master data: Chamber of Commerce numbers whose leading zeros were dropped somewhere along the chain, OIN values containing spaces or hyphens, and VAT numbers stored in lower case or without a country code. While the rules remain warnings, those messages still get through. Once they turn fatal, they will be rejected.

For Peppol Serviceproviders, the practical step is therefore not only to validate but also to report. Collecting the warnings from the current validation cycle and feeding them back per connected customer produces a concrete clean-up list before the next release starts rejecting those messages outright. The same applies to software vendors on the input side: a format check in the source system prevents an incorrectly recorded identifier from ever reaching a Peppol message.

To work out which document types in your own chain are affected, our knowledge base offers an overview of Peppol document types and standards and an explanation of the role of EN 16931 in the validation chain. Looking further ahead, Peppol BIS 4.0 and the PINT and UBL merger is equally relevant, because that transition will again change how country-specific rules are published.

Did your current provider implement the Peppol May Release 2026 late, or fail to inform you about the new warnings? This is a sound moment to test the market. Using the independent comparison tool on Peppol.now, you can compare more than 120 Peppol Serviceproviders on certification, supported document types and country coverage, free of charge and without obligations.

Sources

1. OpenPeppol, Release notes for Peppol BIS Billing v3
2. OpenPeppol, Peppol BIS Billing 3.0 – May 2026 Release
3. OpenPeppol, Release notes for Peppol BIS 3 documents, other than Peppol BIS Billing 3.0
4. OpenPeppol, Peppol BIS version 3 – 2026-Q2 Release
5. Netherlands Peppol Authority, May release of SI-UBL 2 and Peppol BIS 3 published (22 May 2026)
6. Netherlands Peppol Authority, validation artefacts release 2026-05-21 on GitHub
7. Connecting Europe, EN 16931 validation rules 1.3.16
8. AgID, Italian Peppol Authority, Peppol May Release 2026