The so-called "120-day permits" (permits limited to 120 days within 12 months) are popular among foreign workers and their employers. They are not bound by the usual quota limitation applicable to work permits for foreign workers from third countries. However, it is a common misconception that the 120-day permit can be used for any kind of set up where a foreign worker is meant to work in Switzerland during a maximum of 120 days over the course of 12 months. An important differentiation in the law between EU/EFTA and third-country nationals (to the disadvantage of EU/EFTA nationals!) needs to be considered in this context.
According to art. 19 (4)(a)(1) of the Ordinance on Admission, Period of Stay and Employment (OAPSE), non-EU/EFTA nationals can obtain a quota-free work permit for the duration of 120 days within 12 months. Typically, the foreign worker will, in such a case, remain employed under his domestic employment contract and have an agreement with the Swiss company for the 120 days of labor to be carried out in Switzerland. However, he or she is free to be employed either by the Swiss or the foreign entity during that time. The provision does not limit the type of work or services that can be carried out by third-country nationals in such cases (provided they meet the usual requirements for third-country nationals).
For EU/EFTA nationals that wish to work under a 120-day-permit, however, art. 19a (2) OAPSE applies. According to said provision, only cross-border services can be carried out. This means that the worker in question can only obtain a 120-day permit if he or she remains employed solely under his or her domestic contract and is detached to Switzerland by the foreign employer.
This results in a differential treatment to the disadvantage of EU/EFTA nationals given that, with a Swiss contract, an employee does not qualify as such a transborder service provider. In cases where an EU/EFTA is supposed to be detached to Switzerland for up to 120 days under a Swiss contract, there is no option for him or her to do so without taking formal residence in Switzerland and applying for an ordinary work and residence permit.
For any posting of up to 90 days per calendar year (per foreign company and foreign worker), the so-called 90-day notification procedure can be applied both under a domestic and a Swiss contract. However, for any posting supposed to last between 90 days and 120 days, there is a gap for EU/EFTA nationals that does not allow them to work in Switzerland under a Swiss contract without taking residence and obtaining an ordinary work and residence permit.
In any event, a case-by-case assessment is crucial in order to find the ideal setup in these complex situations.