Cross-border employment within the EU comes with complex tax and social-security implications. One of the most important questions for internationally active employees is: which country’s social-security law applies? A recent ruling by the Hoge Raad (Dutch Supreme Court), following guidance from the Court of Justice of the European Union (CJEU), provides clarity. When assessing whether work performed in a worker’s country of residence is “substantial,” the only relevant criteria are the percentage of time worked there and/or wage earned there. The threshold remains strictly 25%.
The case in short
The dispute involved an employee working in several EU countries. The key question was whether this individual performed a substantial part of their work in their country of residence, which determines the applicable social-security legislation.
A lower court previously suggested that additional factors, such as personal situation or ties to the country, could be considered. The CJEU has now rejected that approach.
According to the court, the test must be based exclusively on two objective indicators:
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the expected working time in the country of residence, and
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the expected income earned in that country
If neither reaches 25%, the work is not substantial, meaning social-security contributions are typically due in the employer’s country instead of the country of residence.
As a result, the earlier judgment has been overturned and must be reassessed using this strict approach.
What this means in practice
For cross-border workers and the companies employing them, this decision creates both certainty and structure.
Employees working in multiple EU countries will fall under the social-security legislation of their country of residence only if at least 25% of their working hours or compensation is earned there. If not, they are generally insured in the employer’s country.
This assessment must be forward-looking over the upcoming 12-month period. Historical data may be used, but only to support the forecast.
Other factors, such as family residence, reason for working abroad, or nature of the position, no longer contribute to the assessment.
Impact on certificates and compliance
With this 25% rule reaffirmed, applications for an A1-statement or Certificate of Coverage must be backed by measurable evidence. Authorities increasingly ask for documentation showing working-time distribution and remuneration allocation, especially for frequent cross-border assignments.
Employers therefore need accurate planning, time-tracking, documentation, and compensation breakdowns. Employees should evaluate their expected work pattern before relocating or accepting multi-country responsibilities.
Support with cross-border work and social security
If you are navigating cross-border employment, determining which country’s social-security law applies, or preparing an application for an A1-statement or Certificate of Coverage, TACS Solutions provides guidance and compliance support for internationally mobile employees.