You are residing in France but subjected to the social security legislation of the European country where you are working (EU member state or Switzerland).
You are residing and working in another EU member state (United Kingdom before Brexit, Benelux, Germany, Italy etc.) or in Switzerland – you are subject to the social security legislation of this state.
What is the principle ?
According to the Administrative court decision of 31stMay 2018, to this day the taxpayers who are not affiliated to mandatory social security plan in France are entitled to take advantage of the misunderstanding of the principle of unicity of the social legislation to sustain that it is unfair that their capital revenues have been subjected to contributions and social deductions allocated to finance the Fonds de solidarité vieillesse, to la Caisse d’amortissement of the social debt and to la Caisse nationale de solidarité for the autonomy and therefore require, accordingly, for the discharge of CSG, CRDS, the social security contribution, of the additional contribution to the social security, and solidarity levy.