Generally, the cash received by various departments of China's national economy in their economic activities is deposited in the bank where they open an account, except for the necessary reserve funds, according to the national cash management regulations. The state also encourages savings in the monetary income of individual residents. In order to regulate the currency circulation in a planned way, the People's Bank of China began to make annual cash cashier plans from 1951. The bank plans to withdraw the cash deposited by various departments, units and urban and rural residents according to different categories. The main items are: commodity sales income, labor service income, savings deposit income, tax income, rural credit cooperatives income, post office exchange income and so on. Cash deposited from these aspects can be called money withdrawal, and these items are called money withdrawal channels. The first two items are called goods (services) withdrawal, and the latter items are called credit withdrawal. Generally speaking, the amount of goods returned from circulation accounts for about 71% of the total amount of money returned. This is the currency withdrawal understood from the process and channels of withdrawing cash. In a narrow sense, the withdrawal of money refers to the difference between the cash deposited in the bank and the cash withdrawn from the bank in a certain period, that is, the total bank income MINUS the total bank expenditure, and the difference is positive (> 1) is the currency withdrawal, also known as cash receipt or net cash withdrawal.