Is it legal for schools to recruit cleaning staff to buy social security?

It is legal for schools to recruit cleaning staff to buy social security. The social insurance plan is organized by the government, forcing a certain group to use part of its income as social insurance tax to form a social insurance fund. Under certain conditions, the insured can get fixed income or loss compensation from the fund. It is a redistribution system, and its goal is to ensure the reproduction of material and labor and social stability.