Why do employees in the same unit have the same social security base but different social security contributions?

Legal analysis: employees in the same unit have the same social security base, and the social security contributions are different because employees have different monthly wages and different payment wages. Employees' social security contributions are paid according to the wages declared by the employer in the current month. The wages declared by the employer shall be subject to the wages payable by the employer, and the wages payable shall be lower than 60% of the average wages of employees in the overall planning area in the previous year. If it is higher than the average monthly salary of employees in the overall planning area by 300%, the average monthly salary of employees in the overall planning area shall be 300% as the base.

Legal basis: Article 12 of the Social Insurance Law of People's Republic of China (PRC), the employing unit shall pay the basic old-age insurance premium in proportion to the total wages of its employees as stipulated by the state and record it in the basic old-age insurance pooling fund.

Employees shall pay the basic old-age insurance premium in accordance with the proportion of wages stipulated by the state and record it in their personal accounts.