Companies are required to pay VAT on all sales of goods and services, including imports from other countries. The VAT is not payable, however, if the goods or services are exported.
By the end of each quarter, the company works out how much has been purchased and how much of this is VAT. The company also works out how much is sold domestically and by exportation, and how much of this is VAT. By doing this, the company sees if it has purchased more than it has sold and vice versa.
If the sale-VAT exceeds the purchase-VAT, the company must pay the corresponding amount. On the other hand; if the purchase-VAT exceeds the sale-VAT, the company receives the difference.