Displaying VAT Inclusive Prices
When your prices are uploaded to Magento they are always loaded as net prices. This is because Magento will also apply tax values so we don't want to duplicate it! In order to make your prices appear as inclusive of tax on your webstore you need to change your settings in Magento. Do this at System > Configuration > Sales > Tax, update the prices display under Price Display Settings and Shopping Cart Display Settingsas applicable. You will also need to change your default country to the United Kingdom in the Default Tax Destination Calculation section.
