Is there a way in Exp:resso Store to allow certain customers to be marked tax-exempt and then omit tax based on their status? Ideally a customer would contact us with their tax-exempt number and we would mark them tax-exempt in their member account. Or a member could include their tax-exempt number in a custom field when registering? Once that is filled in for their account, though, how could I omit tax for their orders?
There is nothing out of the box that I know that would allow you to do this. Your best bet would be to create an extension that uses the
store_order_taxes hook to see if the member has a certain field of their profile populated.
Having said that you would probably need to either have only an admin be able to fill out that field or have some logic to make sure that the tax-exempt number is valid so that the end user doesn't just enter a random number.