Due to the implementation of foreign exchange control in China, all external payments must be made through banks, and there is no ready-made foreign exchange in the hands of ordinary enterprises. Therefore, the process of converting RMB into foreign currency through banks and then paying foreign exchange is "purchasing foreign exchange first and then paying foreign exchange".

If an enterprise has enough foreign exchange on its books, it does not need to "purchase foreign exchange first and then pay foreign exchange", and can directly pay foreign exchange with the foreign exchange already on its books.