Tax ID's bring together tax zones and tax categories. In a group of companies, the outcome of the same permutations are different. It would be useful if on the Tax ID screen there is also a Branch/ Company selection so that you can determine the behaviour for that branch.
For Example. We have a branch in Spain and a branch in France. Both deal with the same customer who is in France.
The customer zone is France and the tax category is taxable.
In the case of VAT on an invoice from a French branch to the French customer the charge is 20%
In the case of VAT on an invoice from the Spanish branch to the French customer the charge is 0%
Same tax zone, same tax category but a different required result between branches.