EU VAT Number in shipping address should be used to determine if VAT should be included(?)

Nobody has claimed this yet.

Currently in Magento documentation they instruct to create an Intra-EU tax class with 0% Tax rate for customer group of Intra-EU customers. Tax calculation is set to be based on Shipping Address. Customer is put to the Intra-EU customer group if the Tax number given in registration is valid. It will then show the prices correctly without any VAT / taxes.

If customer then adds an address at the checkout or at the customer account without a Tax number or with invalid Tax / VAT Number it will still show the prices without the taxes, because customer is in the Intra-EU customer group that has 0% tax rate. The invoices in these cases will be incorrect. Also sales for private persons should include VAT.

Shouldn't the tax be added or removed based on the TAX Number on the shipping address instead of the customer group?

I'm not sure I understand why there currently is a separate TAX Number field for the address and why is not the customer account's TAX/VAT number field used.

Start by reviewing the Magento documentation and the described tax configuration for customer groups, shipping addresses, and tax numbers. The issue does not identify implementation files, entry points, or tests, so the expected behavior needs clarification before work can begin. Done would require an agreed rule for how address and customer tax numbers affect VAT calculation and corresponding coverage.

Written by the indexing model from the issue text.