When a Polish Staffing Agency Becomes a Danish Tax Payer: SKAT Rules 2026

For any Polish staffing agency operating in Denmark, the question of when it crosses the line from a foreign service provider into a fully registered Danish taxpayer is one of the most consequential compliance decisions it will face. SKAT, the Danish Tax Authority, has clear rules about when a foreign entity acquires a permanent establishment or an employer status that triggers local tax obligations, and misreading those rules can lead to back-tax assessments, interest charges, and fines that can reach tens of thousands of DKK. This guide walks you through the key thresholds, the documents you need, and the practical steps to register correctly before problems arise.

Step 1: Check Whether Your Agency Has Crossed the Threshold

The first and most critical question is whether your agency has created a permanent establishment (fast driftssted) in Denmark under Danish tax law and the relevant double taxation treaty between Poland and Denmark. As a general rule, a Polish agency that merely seconds workers to Danish clients without maintaining any fixed place of business in Denmark does not automatically become a Danish corporate taxpayer. However, several factors can change that picture quickly.

If your agency maintains a local office, a site hut used exclusively by your own management staff, or a representative who habitually concludes contracts on behalf of the agency in Denmark, SKAT may treat that as a permanent establishment. Duration also matters: construction and assembly projects that last beyond the threshold defined in the Poland-Denmark double taxation treaty can independently create a taxable presence. Beyond corporate tax, there is a separate and equally important question about employer registration. Under Danish rules, a foreign employer that pays wages to workers performing work in Denmark must register as an employer with SKAT and withhold A-skat (income tax) and AM-bidrag (labour market contribution) from those wages. This obligation arises regardless of whether the agency has a permanent establishment for corporate tax purposes.

Before you go further, review the obligations that flow from Worker Rotation on Danish Construction Sites & LOV 89: 2026 Guide, because the rotation rules directly affect how long individual workers stay on a project and therefore how your payroll obligations are structured under SKAT.

Step 2: Gather the Required Documents

Once you have established that registration is required, you need to assemble a specific set of documents. SKAT will ask for proof of the agency's legal existence in Poland, which means a current extract from the Polish National Court Register (KRS), translated into Danish or English. You will also need the agency's Polish tax identification number (NIP), documentation of the contracts with Danish client companies, and a list of the workers being seconded along with their expected start and end dates.

On the Polish side, it is worth coordinating with ZUS at an early stage. If workers remain subject to Polish social security under an A1 certificate issued in accordance with EU Regulation 883/2004, that certificate must be obtained before the workers start in Denmark, not after. ZUS processes A1 applications through its online platform, and delays can leave both the agency and the workers in an uncertain position during inspections by Arbejdstilsynet.

Pay close attention to wage documentation as well. SKAT and Arbejdstilsynet increasingly cross-reference payroll records during joint inspections, and your records must demonstrate that workers are receiving at least the applicable minimum rates. For a clear picture of what those rates look like in the construction sector, see the overview of Minimum Hourly Rates for Construction Workers in Denmark 2026.

Step 3: Fill Out the Registration Forms via the SKAT Portal

Foreign employers register with SKAT through the official Virk portal, which is Denmark's central business registration platform. The relevant form for a foreign employer without a permanent establishment is the registration for begrænset skattepligtig (limited tax liability) employer status. You will need a NemID or MitID Erhverv credential to access the portal, which as a foreign company you can obtain by contacting SKAT's international desk directly.

The registration requires you to specify the expected number of employees, the nature of the work, the anticipated duration of the assignment, and the Danish client's CVR number. SKAT will then issue the agency a SE number, which is the Danish employer identification number used on all payroll filings. The entire process is described in detail on the SKAT official website, where guidance for foreign employers is available in English.

Step 4: Submit Payroll Reports and Withhold Correctly

Once registered, the agency must file monthly payroll reports through the Danish eIndkomst system. Every pay period, A-skat and AM-bidrag must be calculated, withheld from each worker's gross pay, and transferred to SKAT by the deadline, which is typically the last banking day of the month following the pay period. Workers who hold a valid Danish tax card (skattekort) will be taxed at their individual rate; those without one are taxed at the higher trækprocent for non-card holders, which is a significant deduction.

Agencies should also be aware that Danish collective agreements in the construction sector, negotiated between the Danish Construction Association (Dansk Byggeri) and the trade union 3F, set out rules on overtime, night work, and holiday pay that apply to posted workers. Getting those calculations right from the start is essential; a detailed breakdown can be found in the article on Overtime Night & Holiday Pay on Danish Construction Sites 2026.

Step 5: Wait for Confirmation and Monitor Ongoing Obligations

After submitting the registration, SKAT typically issues a confirmation and an SE number within a few weeks, though processing times can vary. Keep a copy of all submitted documents and correspondence. SKAT may request additional information, particularly if the agency is new to the Danish market or if the volume of workers is large. During this waiting period, do not allow workers to begin work in Denmark without at least having submitted the registration; starting work before registration is one of the most common and most costly mistakes agencies make.

Common Mistakes to Avoid

The single most frequent error is assuming that because the agency pays taxes in Poland, it has no obligations in Denmark. The two systems operate independently, and the existence of the Poland-Denmark double taxation agreement does not eliminate the employer registration duty; it only governs how corporate profits are allocated between the two countries. A second common mistake is failing to update SKAT when the scope of work changes, for example when a project is extended beyond its original timeline or when additional workers are added. Changes must be reported promptly. Third, agencies sometimes overlook the obligation to provide workers with Danish-language pay slips that meet the requirements set out under Danish law, even when the employment contract itself is governed by Polish law under the terms of the Posted Workers Directive (Directive 96/71/EC as amended by Directive 2018/957/EU).

Finally, keep your Polish documentation in order as well. PIP, the Polish National Labour Inspectorate, has the authority to audit agencies operating abroad and to share findings with foreign authorities. Maintaining clean records with both ZUS and PIP not only protects the agency at home but also demonstrates good faith to SKAT if an audit arises in Denmark. For authoritative guidance on Polish employer obligations, the ZUS official portal and the PIP website are the primary reference points. Acting early, documenting everything, and treating Danish and Polish compliance as two parallel tracks rather than alternatives is the most reliable way to keep your agency on the right side of SKAT.