Due to the exchange rate problem, the amount paid by the customs does not need to pay VAT. It is not buying or selling foreign exchange, but exchanging more RMB in a time difference, which is equivalent to the nature of profit. Because it is the fluctuating value of RMB, import and export goods before exchange rate adjustment are subject to tax after exchange rate adjustment due to changes in tariff classification, approval of duty-paid price or other reasons of customs work.