How to make the company pay the previous social security?

The way for the company to pay back the previous social security: the parties can negotiate with the company first and let the company pay back. If the company doesn't make up the payment, the parties can carry the labor contract. If there is no contract, they will go to the social security bureau with proof materials such as salary slips, and the social security bureau will order the company to make up the previous social security after verification.