OIOUBL: the Danish e-invoice standard and pioneering format, mandatory for government suppliers since 2005.
OIOUBL (Offentlig Information Online UBL) is the Danish standard for e-invoicing. Denmark was an absolute pioneer: as early as 2005, e-invoicing to government was made mandatory via the NemHandel network and OIOUBL. This made Denmark one of the first countries in the world with mandatory e-invoicing, and the Danish model is frequently cited internationally as best practice.
OIOUBL is a Danish UBL profile with country-specific extensions for the Danish market. The format predates the European standard EN 16931 and therefore has a number of structural differences compared to modern formats like Peppol BIS Billing V3. Historically, OIOUBL invoices were exchanged via the NemHandel network, the Danish precursor to Peppol.
Today, the majority of Danish invoicing runs via the Peppol network. OIOUBL is still in use, but Peppol BIS Billing V3 is the dominant standard for new implementations.
With the transition to Peppol, Denmark supports both OIOUBL and BIS Billing V3. The Peppol Authority (Digitaliseringsstyrelsen) encourages the use of BIS 3.0 for new connections. Specific Danish schemeIDs (e.g. 0184 for Danish recipients since BIS 3.0.20) are required.
eConnect routes invoices to Danish recipients via the Peppol network. The PSB automatically adapts the format and supports the Danish schemeID requirements. Incoming OIOUBL invoices are recognised and processed.