There are two ways to submit your VAT registration number.
Providing your VAT ID when ordering:
After adding an item to your cart and proceeding to the Checkout screen, you will see a field called “VAT / TAX ID”.
Providing your VAT ID after ordering:
Log into the Client Area, click “Hello, <name>!”, and click “Edit Account Details” you will see a field called “VAT / TAX ID”.