When it comes to tax calculation with cash discount in Belgium it works a little different then IFS standard. 

In IFS there is a setting on company which says “tax reduction on discount”. This option lowers the VAT if the payment discount is deducted. 

However how the Belgium TAX system works is that you need to amend the base amount of the tax regardless of if the payment discount is used or not. Are there any other customers that have this issue in Belgium? How do you solve it?