Nordic Peppol Infrastructure Guide
Denmark's Digital Bookkeeping Act Drives Full Peppol Adoption
Denmark pioneered e-invoicing in 2005 and now has 99% B2G adoption. The Bookkeeping Act requires all businesses to use certified digital systems capable of sending and receiving structured e-invoices. The next big shift: OIOUBL retires in 2028, replaced by Nemhandel BIS 4. Here is what software vendors need to build.
Legal Basis
The Danish Bookkeeping Act
Denmark's e-invoicing and digital bookkeeping framework is established under the Bogforingsloven (Bookkeeping Act, Law No. 700 of May 24, 2022). This act mandates the use of certified digital standard bookkeeping systems (DBS) for businesses meeting specific thresholds. These systems must be technically capable of sending and receiving structured electronic invoices via the Peppol or NemHandel networks.
Detailed technical and functional requirements are defined in Executive Order BEK 97 of January 26, 2023. The registration and notification procedure for digital standard bookkeeping systems is set out separately in Executive Order BEK 98 of January 26, 2023.
The Peppol Authority for Denmark is Erhvervsstyrelsen (ERST, the Danish Business Authority). ERST sets local requirements, registers Danish Peppol Access Points and SMP providers, and governs the NemHandel infrastructure.
For software vendors: Denmark's approach is indirect. There is no separate B2B e-invoicing mandate with a specific compliance date. Instead, the Bookkeeping Act requires all in scope businesses to use registered digital accounting systems that support structured e-invoicing. If your platform serves Danish customers, it must be able to send and receive Peppol BIS or OIOUBL invoices as part of its certified bookkeeping functionality.
Implementation Timeline
From B2G pioneer to full Peppol BIS 4 migration
B2G e-invoicing mandatory via NemHandel. Denmark becomes first country to mandate e-invoicing nationally.
Digital bookkeeping requirement begins for companies in accounting Classes B, C and D.
Registered bookkeeping systems must auto-enroll customers in NemHandel and default-prompt e-invoicing.
OIOUBL 3.0 development cancelled. Denmark announces transition to Nemhandel BIS 4 (Peppol BIS 4).
SAF-T 2.0 support mandatory for all registered bookkeeping systems.
Nemhandel BIS 4 release candidate period ends. November 2028 - Nemhandel BIS 4 becomes mandatory; OIOUBL 2.1 becomes voluntary.
OIOUBL 2.1 completely retired. Nemhandel BIS 4 is the sole national format
Network Architecture
NemHandel and Peppol: Two Networks, One Infrastructure
Denmark operates NemHandel, its national e-delivery network, which runs in parallel with the international Peppol network. In practice, both use the same underlying Peppol eDelivery infrastructure and Access Point model. The distinction is primarily about directory routing: domestic Danish transactions resolve through SML-DK, while cross-border transactions route through the standard EU SML.
Denmark uses a post-audit model, not clearance. Invoices flow directly between trading partners through accredited Access Points. The tax authority (Skatteforvaltningen) does not pre-approve invoices. Compliance is monitored through SAF-T audit files and periodic inspections.
The NemHandel Register (NHR) is Denmark's national equivalent of the Peppol Directory. The NHR maps Danish business identifiers (CVR numbers, SE numbers, GLN) to their network endpoints for domestic NemHandel recipients. Senders query the NHR the same way they'd query the Peppol Directory, to confirm a recipient can receive e-invoices.
The OIOUBL 3.0 cancellation (January 2026): Denmark was planning to develop OIOUBL 3.0 as the next generation national format. Instead, the Danish Business Authority cancelled that plan and announced a direct transition to Nemhandel BIS 4, a Danish adaptation of the international Peppol BIS 4 standard. This is a significant strategic signal: Denmark is aligning its domestic format with the global Peppol standard rather than maintaining a proprietary national format.
Format Requirements
From OIOUBL 2.1 to Nemhandel BIS 4: The Migration Path
Current accepted formats:
- OIOUBL 2.1 - The legacy Danish XML standard based on UBL 2.0. Remains valid alongside Peppol BIS Billing 3.0 through the Nemhandel BIS 4 transition, with full retirement expected by May 2029.
- Peppol BIS Billing 3.0 - The European standard aligned with EN 16931. Widely used for both B2G and B2B transactions.
Upcoming format:
- Nemhandel BIS 4 - Danish adaptation of Peppol BIS 4 using the PINT (Peppol International Invoice) architecture. Ensures domestic e-invoicing is fully aligned with global Peppol infrastructure.
What is not accepted:
- PDF or Paper invoices for B2G transactions
- Unstructured email attachments
- EDI formats not aligned with EN 16931 or OIOUBL
Recipients are identified by their CVR number (Danish business registration number) or SE number (VAT number) in the NemHandel Register. The NHR maps these identifiers to network endpoints for routing.
Already on Peppol? If your platform supports Peppol BIS Billing 3.0 for other markets, you are already compliant with Danish B2G requirements. The Nemhandel BIS 4 transition is the next step, but Peppol BIS 3.0 remains fully accepted until the phase-out begins in May 2028. Your format work for Denmark is essentially done if you are on Peppol today.
Denmark at a Glance
Key Facts for Software Vendors
Everything you need to know before your next sprint planning session.
Legacy Danish XML standard based on UBL 2.0. Peppol BIS Billing 3.0 also accepted. Both remain valid until Nemhandel BIS 4 phase-in begins in May 2028.
No clearance or pre-approval. Invoices flow directly between partners via Peppol or NemHandel. Tax authority monitors via SAF-T audit files and periodic inspections.
Sole proprietors with net annual turnover exceeding DKK 300,000 for two consecutive years must comply. Below that threshold, exemption applies. Classes B, C, D already in scope.
Fines range from DKK 10,000 to DKK 1,500,000 (approx EUR 200,000), scaled by company turnover. Persistent non compliance can lead to compulsory dissolution.
All registered bookkeeping systems must support SAF-T 2.0 with expanded transaction level structures (MIFU). Standardized audit file for Skatteforvaltningen inspections.
Nearly all B2G invoices in Denmark are already transmitted electronically. The infrastructure is proven, stable, and deeply embedded.
Scope and Exemptions
Who Must Comply and Who Is Exempt
The Danish Bookkeeping Act applies to businesses in three tiers based on accounting class and turnover:
- Classes B, C, and D (companies required to submit annual reports): Required to use registered digital bookkeeping systems since July 2024 (or January 2025 for those using customized systems).
- Sole proprietors and partnerships with net annual turnover exceeding DKK 300,000 for two consecutive fiscal years: Required since January 1, 2026.
- All public entities and their B2G suppliers: suppliers required to send and public entities to receive structured e-invoices.
Exemptions:
- Micro-businesses and sole proprietors with annual net turnover below DKK 300,000
- Foreign entities without a permanent establishment in Denmark (not subject to Danish bookkeeping regulations)
- B2C transactions (not covered by the B2G mandate or the bookkeeping e-invoicing capability requirement in the same way)
Action Plan
Vendor Readiness Checklist: Q3 2026 to 2029
The critical preparation window is 2027 to 2028, when SAF-T 2.0 and the Nemhandel BIS 4 format migration both hit. Plan now.
Verify Peppol connectivity. If you already support Peppol BIS Billing 3.0 for other markets, you are compliant for Danish B2G and B2B today. Confirm your Access Point routes to NemHandel via SML-DK for domestic Danish recipients.
Check your customer base against NHR. Query the NemHandel Register to confirm which of your Danish customers are already registered to receive e-invoices. Most will be.
Audit your bookkeeping system certification. If your platform is used for Danish bookkeeping, confirm it is registered with Erhvervsstyrelsen as a Digital Standard Bookkeeping System (DBS).
Implement SAF-T 2.0 export. Your registered bookkeeping system must support the expanded SAF-T 2.0 format with MIFU transaction level structures from January 1, 2027. This is a hard deadline.
Test SAF-T output with Skatteforvaltningen. Validate that your generated SAF-T 2.0 files pass validation checks. Use the official test tools provided by the Danish Tax Agency.
Prepare for Nemhandel BIS 4. Monitor the release candidate (November 2027 to May 2028). Begin implementation during the release candidate phase so you are ready for the May 2028 final release.
Support dual format during transition. Between May and November 2028, both Nemhandel BIS 4 and OIOUBL 2.1 must be supported. Build format detection or configuration to handle both.
Plan OIOUBL 2.1 retirement. By May 2029, OIOUBL 2.1 will be fully retired. Ensure all customers are migrated to Nemhandel BIS 4 before that date. Build automated migration tooling.
Frequently Asked Questions
Denmark E-Invoicing: Technical and Compliance Questions
Not as a direct transaction level mandate. Denmark takes an indirect approach: the Bookkeeping Act requires businesses to use certified digital bookkeeping systems that are technically capable of sending and receiving structured electronic invoices (Peppol BIS or OIOUBL). If your customers or suppliers are on the NemHandel or Peppol network, your system must be able to exchange structured e-invoices with them. The government has not set a specific date for mandatory B2B e-invoice issuance, but the digital bookkeeping requirement effectively forces the capability.
OIOUBL 2.1 is the legacy Danish XML format based on UBL 2.0, used since the early days of NemHandel. Nemhandel BIS 4 is the upcoming replacement, built as a Danish adaptation of the international Peppol BIS 4 standard using the PINT (Peppol International Invoice) architecture. The critical change: Denmark cancelled the planned OIOUBL 3.0 in January 2026 and chose to align directly with the international Peppol BIS 4 standard instead. This means the future of Danish e-invoicing is fully Peppol, not a proprietary national format.
The migration is phased. The release candidate of Nemhandel BIS 4 arrives between November 2027 and May 2028. The final version is expected in May 2028, after which it becomes voluntary while OIOUBL 2.1 remains supported. Between May and November 2028, Nemhandel BIS 4 becomes mandatory and OIOUBL 2.1 becomes voluntary. By November 2028 to May 2029, OIOUBL 2.1 will be completely retired. Software vendors should plan to support both formats during the transition window and build for Peppol BIS 4 as the end state.
SML-DK is Denmark's dedicated Service Metadata Locator, launched in November 2024 and fully migrated by December 2024. Previously, Danish NemHandel recipients were registered in the shared European SML. Denmark separated its national directory to maintain sovereign control over domestic e-delivery registrations. NemHandel-only registrations now live exclusively in SML-DK, while businesses with active international Peppol registrations remain in the EU SML. For software vendors, this means recipient lookup for purely domestic Danish transactions queries SML-DK, while cross-border Peppol transactions use the standard EU SML. Your Access Point provider should handle this routing automatically.
SAF-T (Standard Audit File for Tax) is the Danish tax audit data format used by Skatteforvaltningen (the Danish Tax Agency). From January 1, 2027, all registered digital bookkeeping systems must support SAF-T 2.0, which includes expanded transaction level structures (called MIFU, or Mandatory If Used). This is not real time reporting like Italy or Poland. It is a standardized audit file that tax authorities can request during inspections. Your accounting software must be able to generate valid SAF-T 2.0 exports from that date.
Only if your company has a permanent establishment in Denmark and is subject to Danish bookkeeping regulations. Foreign entities without a Danish presence are not required to use a registered digital bookkeeping system. However, if you sell to Danish businesses or government entities, you will need to send and receive structured e-invoices via the Peppol or NemHandel network. That means connecting to a certifeed Access Point, even if you are not subject to the Bookkeeping Act itself.
Penalties under the Bookkeeping Act range from DKK 10,000 to DKK 1,500,000 (approximately EUR 200,000), scaled based on company turnover. In extreme cases of persistent non compliance, the Danish Business Authority can request compulsory dissolution of the company. These penalties apply to failures in digital bookkeeping, not specifically to e-invoice format violations. However, since e-invoicing capability is a required function of certified bookkeeping systems, failing to support it puts businesses in penalty territory.
Denmark's indirect, bookkeeping-led approach differs from Norway's direct B2B mandate and Sweden's still-developing framework, with a clearer migration path to Peppol BIS 4. For software vendors operating across the Nordics, Denmark is an easy market to support today because the infrastructure is already built. The key task is preparing for the OIOUBL to Nemhandel BIS 4 transition starting in late 2027.
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