Denmark Pushes Back OIOUBL 3.0 Launch, Tightens Validation Rules on Current Standard

Denmark has delayed the rollout of OIOUBL 3.0, its updated national e-invoicing standard, until October 2025, with mandatory use starting May 15, 2026. In the meantime, OIOUBL 2.1 will remain active, but stricter validation rules took effect on May 15, 2025, including tighter VAT consistency checks. Businesses and software providers must now comply with enhanced validations under OIOUBL 2.1 while preparing for the future transition to version 3.0.

The Danish Business Authority has officially postponed the launch of OIOUBL 3.0, the next major version of Denmark’s national e-invoicing standard. The release, originally scheduled for spring 2025, has been pushed back by six months to allow more time for analysis and to resolve outstanding issues.

New timeline for OIOUBL 3.0 implementation:

-          October 2025: Final version of OIOUBL 3.0 released,

-          May 15, 2026: OIOUBL 3.0 becomes mandatory on NemHandel.

-          November 15, 2026: OIOUBL 2.1 officially phased out.

OIOUBL is one of Denmark’s two official e-invoicing standards, alongside Peppol BIS 3.0. The updated OIOUBL 3.0 will offer improved formats for invoices, credit notes, and response messages and will better align with the European standard EN 16931.

Since OIOUBL 3.0 is delayed, OIOUBL 2.1 will remain in use for over a year. However, stricter validation rules took effect on May 15, 2025, with the mandatory use of schematron version 1.15.2.

These changes don’t introduce new VAT laws but enforce tighter technical checks on existing requirements:

-          Zero-rated items must show 0% VAT and 0 DKK TaxAmount.

-          Standard-rated items must show correctly calculated VAT (±1 DKK tolerance).

-          Invoice-level TaxableAmount must match the sum of line-level taxable amounts (±1 DKK tolerance).

A detailed list of the updated rules and format changes has been published to help users stay compliant.

For businesses and software providers, the message is clear: Prepare for stricter validation under OIOUBL 2.1 now, while planning for the transition to OIOUBL 3.0 in 2026.