Conditions on proof of payment for consideration of tax refund with regard to exported goods for which payment is made by debt offsetting are regulated at clause 4 Appendix VII of Circular No. 38/2015/TT-BTC .
Accordingly, in case payment for exports are made by offsetting the value of the exported goods against the value of goods, service bought from the foreign party, the application for duty refund shall be considered satisfaction of conditions on payment via wire transfer if these conditions are met:
(i) The payment method is specified in the export contract;
(ii) There is a written confirmation of the foreign party about the offsetting;
(iii) The difference (if any) between amount of exports and amount of imports is paid via wire transfer.