A friend is a Swiss citizen but lives abroad (Auslandschweizer). He wants to visit Switzerland on holiday, i.e. maintaining his domicile in his other country.
While he's here for just a few weeks, he'd have the opportunity to work (with a contract) part-time and temporarily, for his former employer. He wants to be an employee, but will not be registered (angemeldet) as living in Switzerland (because he doesn't).
The employer would have to make the usual AHV deductions and pay those in, and mandatory accident insurance.
Does he or does the employer have to do anything else, for this to be permissible? Tax, presumably, is in his country of domicile.