Adding a VAT exempt tax to order lines automatically

Aske_Holst

I have customer selling widgets subject to a widgets tax. The tax is a set amount specific to each item. This is specified on each item (actually it is a number of groups and rules, but to make it simple think of it as a fixed amount per item).
Example:
Widget A: Price 100, tax 2, VAT 25%
Widget B: Price 150, tax 10, VAT 25%

The tax amount MUST be shown on each order line, per unit and total. Not as a separate line (although it is ok to have separate lines in invoicing)

The tax is NOT to be included in VAT calculation.

Example order:
Widget A, Qty 4, Price 100, Amount 400,  Tax amount 8, VAT 100
Widget B, Qty 2, Price 150, Amount 300,  Tax amount 20, VAT 75

Example invoice:
Widget A, Qty 4, Price 100, Amount 400, VAT 100, Total 500
     Tax, Qty 4, Price 2,   Amount 8
Widget B, Qty 2, Price 150, Amount 300, VAT 75,  Total 375
     Tax, Qty 2, Price 10,   Amount 20
                                       Total excl. VAT 728
                                                   VAT 175
                                       Total incl. VAT 903

The question is how to do this the NAV-way, surely some customization is need but I would like to stay way from changing the posting (CU80).

Would creating an extra order line OnInsert with the tax for each item order line be a reasonable idea? The line could be hidden in the order form but otherwise be a regular order line, the amount showing up in flowfields on the order line.

Any suggestions? - It seems that someone have solved this before.