How do you add rules to specify zero rate VAT when a VAT number is supplied? I'm using the Commerce VAT, Commerce EU VAT and VAT Number modules and would like to add a rule so that if someone is within the EU (but not in the UK) and enters a valid VAT number, the VAT rate is set to zero rate.

Our current setup is working so that purchases from within the United Kingdom are being charged VAT, purchases from outside the EU are not, but I've also added the VAT Number module so that people who are in the EU but not in the UK are charged zero rate tax.

I've overwritten the validation function within the VAT Number to bypass the SOAP server for the purposes of testing, but when I get through with a, say, FRXX ** VAT Number, the full 20% is still being added. I'm guess I need to create a rule to work with the VAT Number, but I can't see how or where, as I'm still relatively new to Rules.

How do I create a rule so that the VAT rate on an order changes to zero rated when the customer supplies a valid VAT number, is within the EU and not in the UK?

Any help here would be appreciated.
The rules for adding zero-rated VAT to other EU countries when a valid VAT Number is supplied are added when you enable the 'Commerce EU VAT Intra-community Supply' module in the 'COMMERCE EU VAT' module group.