When I offer a product with 100% discount, so price is ZERO, Shopify does not apply taxes to shipping cost. Charge and report tax over shipping is a legal requirement, so I think it is Shopify defect.
Two samples: First one shows VAT calculated over the sum of product price (8.99) and and price of shipping (4.99). The second one has no VAT at all, so it is illegal.
Can anybody help, please?