EU Regulation (EC) 883/04 states that in principle the social security legislation of the employee’s state of residence applies when he or she simultaneously works in several EU Member States, including substantially (25% or more) in the country of residence.
The Dutch Central Appeals Council (Centrale Raad van Beroep) recently ruled in a case where an employee worked from home the majority of the time for an employer based in another EU Member State. The Central Board of Appeal ruled that the legislation of the state of residence only applies if the employer has agreed (which can also be an implicit permission) to working from home, knowing that the employee lives in another EU country. The working pattern alone is not decisive.
Previous rulings by the European Court on this were less far-reaching. As a result, it cannot be ruled out that mismatches will occur compared with other EU countries.