Import gross sum and let Mamut calculate vat. (Recommended)
To use this method make sure the last two fields are used.
Gross is set to either T or F (see more about Gross above)
GrossSum is numeric with three decimals and shall have the gross sum (incl. vat).
Set VAT code to 1 on the 1510 rows and relevant VAT code on e.g. 3010 rows.