From the official documentation I read this :
Enable B2B mode. New in 1.5. The B2B mode brings a handful of new features to your store. Customers are no longer considered as individuals but as companies, and therefore some new options appear:The customer profile has new fields related to professional information (Duns number in the USA, SIRET number in France, CNPJ number in Brazil, etc.),
Prices can be masked to specific groups,
Prices can be managed on a per-customer basis for the whole catalog or per category,
Invoices can be generated manually,
etc.
I activated the B2B option, but I haven't noticed any new fields/options ... I installed the module for the VAT number : now if a user fills in the field " Company", the "VAT number" fields appears.
However, I created a special group that has a discount for the members that are in, but I noticed that I have to manually include an user to this new group: isn't there an option that can automatically include a user, who has a VAT number, to this group?