Throughout the history of the People's Republic, the banking system has exerted close control over financial transactions and the money supply. All government departments, publicly and collectively owned economic units, and social, political, military, and educational organizations were required to hold their financial balances as bank deposits. They were also instructed to keep on hand only enough cash to meet daily expenses; all major financial transactions were to be conducted through banks. Payment for goods and services exchanged by economic units was accomplished by debiting the account of the purchasing unit and crediting that of the selling unit by the appropriate amount. This practice effectively helped to minimize the need for currency.