Anyone who is working as an employee ("Arbeitnehmer") and earns more than 450 euros per month, have to make social security contributions in Germany. If you earn less (i.e. have a € 450-job), you are exempt from social security contributions. Those who are self-employed can voluntarily make contributions and acquire coverage. You can find out more in our chapters "Mini-job", "Starting up a Registered Business ("Gewerbe")" and "Starting up as Self-Employed ("Freiberufler")".
Please note: Everyone in Germany must be covered by health insurance, regardless of their jobs entailing social insurance contributions or otherwise. You can read more in our chapter "Health insurance".