In a globalizing world, national borders are frequently crossed. Moreover, flexibility is a key skill in the knowledge economy of the 21st century. Accordingly, an increasing number of workers can be labelled as ‘highly mobile’. Thia are persons that combine various forms of work (on-call contracts, employment agency work, platform- work, teleworking etc.) that are carried out in several countries.

In a European market in which free movement rights are considered fundamental, this research demonstrates that the current EU coordination instrument of social security may give rise to various issues of legal uncertainty for those highly mobile cross-border workers. This is problematic as this is not only cumbersome for administrative matters, but may also result in no or very limited social protection for the highly mobile worker.

With many forms of flexible work and work activities increasingly being performed in several Member States, it seems more important than ever to map out mobility-related issues that highly mobile workers may encounter and to explore possible routes towards more legal certainty regarding their social security protection. That is, exactly, what this research aims to attain.