Self-employed people are in charge of their own social security. The four basic duties apply to all self-employed people, whether in primary or secondary profession. The only difference lies in the size of the obligatory contributions to the social security system.
Every self-employed person, whether primarily or secondarily self-employed, has to join a social insurance fund.
In order to enjoy social security, you need to pay social contributions. Every self-employed person, whether primarily or secondarily self-employed, and all companies have to comply with this duty.