Depending on your location you may be requested to provide your VAT registration number under your Billing information; it is a required field. If your company does not yet have a VAT number, you could circumvent this requirement by adding a dash "-" in the VAT field. However, you will still be charged the VAT, no matter which EU country you are registered in.
When you have a pending payment or an active subscription it is not possible to manually change your VAT registration number or the country in your billing address. Contact our support team for assistance.