Hey there, I believe validating VAT numbers is outside of the Stripe tax pricing and part of the Customer Tax IDs API, without any extra charge. Maybe someone from Stripe can confirm?

https://stripe.com/docs/billing/customer/tax-ids

And yes, if you sell only to B2B Europe and everyone inputs their VAT number you're fine (because you actually don't have to charge VAT, it's a reverse charge). Stripe tax do know this nowadays.

But that's actually not so common, people signing up for products usually have no idea what the VAT number of their company is. But they are capable of getting a credit card and giving you a business address.

In this case, you have to compute VAT rates based on the country of the customer.

(This is not an accounting advice, just personal experience!)