Is the social security nationwide or the city where I pay?

Social security is national. At present, the country has clearly stipulated that it can be used across provinces, but the reimbursement amount used across provinces is different from that of the province (the paying province), and the procedures and material preparation of each reimbursement place will be different. At present, some provinces have realized the one-card swipe card in the province, which is very convenient for on-site settlement of medical treatment in different places. The country said many years ago that social security will eventually circulate throughout the country. Just like the ID card, you can use it anywhere as long as you have a card for medical treatment, but it is not perfect at present.