According to Official Dispatch No. 1506/TCT-CS dated April 18, 2019, in case an enterprise has both exported goods and services and domestically sold goods and services in the month/quarter, the enterprise must account for separate VAT input amount used for production and trading of exported goods and services (including fixed assets).
In case the enterprise can not account separately, the VAT input amount of exported goods and services is determined according to the ratio between the revenue of exported goods and services to the total revenue of goods and services of the enterprise of all VAT declaration periods. And they are calculated from the tax declaration period following the previous tax refund period to the current tax refund request period.
The VAT input amount of exported goods and services (including the VAT input amount that can be accounted for separately and the input VAT amount allocated according to the ratio of revenue) will be considered for refund. If after offsetting it againsts the VAT output amount of domestically sold goods and services, the remaining amount is from VND 300 million or more. And the maximum refundable tax amount shall not exceed 10% of the revenue of exported goods and services.