If you are subject to VAT (professionals, sole proprietors, and freelancers), you can enter your VAT number when subscribing to Smash so that VAT can be deducted from the final amount.
Once the invoice has been issued, you can access it from your Smash account under Administration > Billing. It is not possible to change the VAT number on an invoice that has already been issued, for accounting and tax reasons.
However, your billing information (first name, last name, address) can be updated in your account so that it appears correctly on your future invoices.
If you need to update your VAT number, you will need to cancel your subscription and then subscribe again, entering the correct information.