The labor law stipulates when to buy social security.

Legal analysis: There is no clear stipulation in the Labor Law, but as far as the legislative spirit of the Labor Contract Law is concerned, when the laborer and the employer form a de facto labor relationship, the employer will purchase social security for the laborer. At the latest, social security should be purchased for workers within one month after the establishment of factual labor relations. According to other relevant laws and regulations, the employer shall handle social insurance registration for its employees within 30 days from the date of employment.

Legal basis: Article 72 of the Labor Law of People's Republic of China (PRC) determines the sources of social insurance funds according to the types of insurance, and gradually implements social overall planning. Employers and workers must participate in social insurance and pay social insurance premiums according to law.

Article 58 of the Social Insurance Law of People's Republic of China (PRC) * * * The employer 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.