The customs declaration is a certificate to prove the export of goods, which is used for verification and tax refund. All export commodities are available.

The foreign exchange payment voucher is a voucher issued to you by the freight forwarding company. Compared with the nature of sea freight invoices, they are used to purchase foreign exchange from banks. There is no such thing under FOB or other trading conditions without paying sea freight.

If it is exported by your company, you must have a customs declaration form. You need to contact the freight forwarder. You can't cancel the tax refund without this.