How do I add VAT to a payment amount in a form?

When you add a purchasable item you will see a check box which controls the ability to add tax (VAT) to it. We've used the phrase tax to cater for wider use cases.

As you can see when this is checked this shows as follows:

This allows you to enter the amount without Tax, the % of Tax (20 for VAT) and also the amount that this equates to. We have now updated the integration mechanism with Capita such that this is automatically passed through the API.