What does it mean to make up the base difference?

This statement means that there is a gap between the social security payment base and the actual salary, and the amount of this gap needs to be paid.

Social security base refers to the basic base for the insured to pay social insurance, which is an important basis for the insured to enjoy social insurance benefits. According to national regulations, the social security base should be consistent with the actual salary of the insured, but in practice, there may be a gap between the social security base and the actual salary for various reasons.

If the social security base is lower than the actual salary, the social security benefits that the insured will enjoy in the future will be reduced, so it is necessary to make up the base difference. The specific amount of the supplementary base difference depends on the difference between the actual salary and the social security base.