Suppose we add 10 items for 10 euro each, total 100 euros (no item tax in this example). Then we need to make a discount of 10 euros (per invoice not per item), so the total goes to 90. And then we need to add the invoice tax, for example 23%.
In such a case the formula would be: 10 x 10 = 100 - 10 (inv. discount) = 90 + 23% = 110,7
As it is now, IP calculates the invoice discount like this:
10 x 10 = 100 + 23% = 123 - 10 (inv. discount) = 113
Is there an option to calculate the discount before invoice tax or will there be any in the future?
Please check this issue. You are not allowed to apply taxes to amounts that are not being paid.
Taxes must apply after any discount or charge is applied, to the final price (before taxes)