Does the new company Shanghai 17 pay social security?

According to the law, employees have to pay social security as long as they join the company in the current month. At present, Shanghai social security department handles social security registration and payment within 5 to 26 days of each month. In other words, employees who join the company before 26th of each month are required to pay social security, which can be paid in (except that paid by the former company in the current month). At the same time, there is also an operating standard in Shanghai, which is that the company can negotiate with employees about the social security payment this month in the month when new employees join the company, including the base of social security payment and whether to pay or repay it in that month, including employees who join the company after 26th.