Tax (VAT) exemption based on filling in a form and ticking a box

[mth1]

I have a potential customer who sells medical equipment. Some of th eitems are eligible for VAT tax exemption (basically 20% off) if the user ticks a box saying they are exempt from VAT as they have an approved medical condition. They then need to complete a quick form outlining their condition. Once they have done this, 20% VAT tax is taken off the eligible products and they can place the order and pay.

My question is this: is there a Shopify module/component available off the shelf, or would this require custom form and flow development?

[mth1]

I should add that the retailer can block the sale after purchase if the form hasn't been completed correctly, so we don't need to fact check on the form.