If you are located within the UK, VAT will be added. You will be able to add your company VAT number and a VAT invoice will be issued.
If you are located in the EU and have a valid VAT/Tax number then tax will be reverse charged meaning you will need to account for this to your local tax authority.
If you are located anywhere else in the world then VAT/Tax will not be added.
For further information please see the European Commission website. http://ec.europa.eu/taxation_customs/business/vat/eu-vat-rules-topic/where-tax_en