Why does social security hang in other people's companies?

Legal analysis: if it is affiliated, it should bear the proportion of companies and individuals. Linking is ok, but since you are not an employee of his company, this behavior is illegal. You can negotiate with your friend's company and sign a social security convergence agreement.

Legal basis: People's Republic of China (PRC) Social Insurance Law.

Article 58 An employing unit shall, within 30 days from the date of employment, apply to the social insurance agency for social insurance registration for its employees. If the social insurance has not been registered, the social insurance agency shall verify the social insurance premium it should pay.

Employees-free individual industrial and commercial households who voluntarily participate in social insurance, part-time employees who do not participate in social insurance in the employing unit and other flexible employees shall apply to the social insurance agency for social insurance registration.

The state establishes a national unified personal social security number. Personal social security number is a citizen's identity number.

Article 60 The employing unit shall declare on its own and pay social insurance premiums in full and on time. Except for legal reasons such as force majeure, the payment shall not be postponed or reduced. The social insurance premiums that employees should pay shall be withheld and remitted by the employer, and the employer shall inform me of the details of paying social insurance premiums on a monthly basis.

Individual industrial and commercial households without employees, part-time employees who have not participated in social insurance in the employing units and other flexible employees can pay social insurance premiums directly to the social insurance premium collection agencies.