Is it so expensive and cost-effective to pay social security yourself now?

It's not cost-effective to pay social security yourself. If the employer participates in insurance for employees, it shall be paid by both the employer and the employees, and the proportion paid by the employer is higher than that of the employees. If you pay social security yourself, the insured person needs to bear all the expenses of social security.

Legal objectivity:

Article 58 of the Social Insurance Law of People's Republic of China (PRC), the employing unit shall, within 30 days from the date of employment, apply to the social insurance agency for social insurance registration for 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.