The best way to deal with it is to add $9, in excess foreign exchange settlement to the customs declaration for the next export. Of course, you can also go to the customs to reissue the customs declaration form as a package for export with the goods and refund the tax separately.

if the business volume is large, it can be communicated with the foreign exchange bureau. for example, it is ok to write off or waive this amount in the next time.

This has little to do with the national tax for the time being. After the verification of foreign exchange receipt, the tax refund is only related to the customs declaration.