Is the Shanghai social security card number M 50 temporary?

The social security account number should be based on the "ID number". Theoretically, a person can only have one social security number in one place, and the overpaid part should be returned. There is no so-called temporary account. Now Shanghai pays social security in a unified way. As long as you work in Shanghai or have a Shanghai household registration, you can pay social security. Now, you just haven't transferred the part you handed in before to Shanghai. This does not affect your actual social security payment. Now you can go to Nanjing to transfer social security, and then go back to Shanghai to transfer. You don't need to move from the beginning. It is very common to work across provinces and cities now. As one of the largest floating cities in China, Shanghai has long had experience in this field, so don't worry.