We are working on a new plugin, that will be ready in around 2 weeks.
s2VatID - if you are asking for VAT ID at the registration form, it will check if the entered VAT ID is valid by verifying it directly at www.ec.europa.eu/taxation_customs/vies/
On the picture below can see how the plugin will work: if the user tries to submit VAT ID that is not valid, s2VatID will display an alert.
If the user doesn’t enter any VAT ID, the plugin will do nothing.
We already offer these s2member addons: