What the agreement covers
The regulation requires the European Commission to build a multilingual public interface through which companies can submit posting declarations. The key mechanics are straightforward: a standardised electronic form, no additional data fields beyond what the system requires, the ability to upload supporting documents and communicate with authorities in one place, and access for posted workers to receive electronic extracts of their declarations.
According to the European Commission, the standardised electronic form reduces the time companies spend on posting declarations by 73%, with administrative cost savings of 58%, even assuming only partial member state participation. If all 27 member states were to adopt the system, that burden reduction rises to 81%.
Those are meaningful numbers. The catch is in the conditions attached to them.
The complication: participation is voluntary
Member states are not required to use the EU interface. Each country decides independently whether to adopt it. If a member state opts in, it must rely exclusively on the EU system and cannot require parallel national declarations. If it does not, its existing national system continues unchanged.
The 81% figure assumes full participation. Partial participation produces a more complicated picture. An employer managing assignments into six EU member states could find itself operating across a mixture of the EU interface and several different national systems, depending on which countries have opted in and when. The administrative saving per posting varies depending on the destination country, not the regulation itself.
Monitoring which countries adopt the system, and when, is not an incidental task. It is a material compliance variable.
What this means for employers posting into Denmark
Denmark currently requires foreign companies posting workers here to register in the RUT (Register of Foreign Service Providers, Registret for Udenlandske Tjenesteydere) system before work begins. Late registration triggers fines from the Danish Working Environment Authority (Arbejdstilsynet).
Whether Denmark opts into the EU interface, and when, will determine whether that RUT registration process changes. No decision has been announced. Until one is, the existing RUT obligation applies in full. Employers posting workers to Denmark should not assume anything changes on the basis of the provisional agreement alone.
The posting compliance picture beyond the declaration
A posting declaration is the visible part of the compliance obligation. The full picture is wider.
When an employee is posted to another EU country, the employer must also confirm which country’s social security system applies. An A1 certificate, issued under EU Regulation 883/2004, documents that the employee remains covered by their home country’s social security during the posting. Without it, dual social security contributions can arise in both the sending and receiving country.
For employees who maintain a home country payroll during a posting, a shadow payroll may also be required in the host country. This calculates the host country tax liability alongside the home country payroll, ensuring both jurisdictions receive what they are owed and the employee’s net position is correctly managed. Where the sending and receiving countries have a double taxation agreement (DTA) in place, the shadow payroll calculation must reflect that treaty position.
These obligations run in parallel with the declaration. Streamlining the declaration process through the EU interface, if a country opts in, does not affect the A1 requirement or the shadow payroll obligation. They remain.
How we handle it
We manage the full posting compliance stack for employers with workers moving across EU borders.
For companies posting workers into Denmark, we handle RUT registration before work begins, ensuring the notification is filed correctly and on time. When Denmark’s position on the EU interface becomes clear, we will update our process accordingly and inform clients of any change to their obligations.
On social security, we handle A1 certificate applications under EU Regulation 883/2004, including the analysis of which country’s system applies and the supporting documentation the relevant authority requires. For multi-state workers or extended postings, we manage extensions and monitor changes in circumstance that could affect the certificate’s validity.
Where a shadow payroll is required, we calculate the host country tax position alongside the home country payroll, coordinate between the two jurisdictions, and ensure the employee’s payslip reflects the correct net outcome. We also manage the authority reporting obligations in each country involved.
For employers with cross-border payroll running across multiple EU countries, we track the adoption of the EU declaration interface as member states make their decisions. That monitoring is part of what we do, not something we expect clients to manage themselves.
If you are posting workers into Denmark or across EU borders and want to understand your current obligations, book a meeting with us.
