What is the loss for the company to pay social security for employees?

There is no loss, but it is good. It is an obligation for the company to pay social insurance for its employees, and it is not allowed to deduct it in cash. If an employee complains back to you and you don't pay insurance for him, you will be in trouble instead.

The only thing that has a little impact is that the part that she has to pay for the three-month insurance is estimated to be sent to her by your company in the form of monetary salary. It's best to discuss with her and let her take on the personal part.