Not all assistants are required to join a social insurance fund.
The obligation to join a social insurance fund is related to the insurance obligation. Assistants who do not fall under the insurance obligation do not have to join a social insurance fund.

This goes for:

• students giving the right to child benefit

• assistants who work less than 90 days per year, whereby their activity is not regular

• assistants younger than 20 (= before January 1st of the year in which they reach the age of 20)
  Attention! Married assistants younger than 20 must join a social insurance fund. They must do so as from the calendar quarter in which they were married.