VAT validation in My Account Addresses

The EU VAT Assistant only validates VAT numbers at checkout. This is by design, as that’s where it’s important that the VAT number is actually valid. If a customer enters the wrong VAT number during the registration, the EU VAT Assistant will stop the checkout, allowing them to rectify the error. The plugin will then save the last valid VAT number against customer’s account.

If you wish to validate the VAT number during the registration, or at any other stage, you can use the filter provided by the EU VAT Assistant for that purpose (see https://wordpress.org/support/topic/faq-validate-eu-vat-number-via-code/). You will have to intercept the registration process, as well as the “save” operation on the My Account page, and call the validation filter there.