Anwar,
Create a condition table with fields Departure country / Destination country / Customer group 1
Put this condition table "at the top" in your access sequence.
Also have the exclusive indicator activated for this condition table.
In VK11, maintain the value of this condition record = 0.
By the above set up, if the customer belongs to that particular Customer group 1, then the value of tax would be zero.
If the customer does not belong to Customer group 1, then the value of the tax would be 14%.