I have been testing the tax exempt mod,
I need it for medical exempt customers to choose there VAT option,
then to buy the product without an admin to make the setting change.

VAT free status will then be checked after the customer makes the purchase.

I will need the customer to complete an online form with exempt questions, is this easiest to put at the checkout or when customer registers?

Thanks for any help.

I prefer to use zen cart but if this is not possible, which cart can handle these options.