Why does social security buy in the local tax bureau?

At present, the collection system of social insurance premiums in different regions of China is not unified, forming different collection models. To sum up, there are two main categories: one is the "social security collection model", that is, the social insurance agency is responsible for collecting social insurance premiums. The other is the "tax collection mode", which is divided into two types: one is the "tax collection mode", that is, the social insurance agency is responsible for verifying the payment amount and the tax department is responsible for collecting it; The second is "tax full responsibility collection", that is, the tax department is responsible for all the collection links including the verification and collection of payment amount. Judging from the collection pattern of social insurance premiums across the country, the areas where social security and tax collection are implemented generally account for half of the country.