Modified VAT Calculation

Hi All,

do any of you have tried doing customization in VAT calculation?

Navision calculation of VAT is by transaction line level. However in the case of my customer, they do the calculation at the subtotal of the whole transaction. The two mentioned calculation has difference, if you apply rounding’s into each calculated VAT amounts.
As a workaround,I have suggested them to use the feature “Allow VAT Difference”. However, this functionality will only work if the user alters the VAT calculated amount by the system. The user don’t want this process, as it would cause them additional step for updating. So in additional to the suggestion, we recommend to help them by adding an automatic calculation of VAT based on the subtotal of the transaction and adjust the amount into the VAT Amount field in the statistics.
what do you think?
if i do the customization.where it should be?