Custom taxable fee problem

Hi everyone,

i am struggling with tax problem of custom fee. I add custom fee with parameter taxable set to true $cart->add_fee("Fee", 5, true) and i also have set standard tax rate. But when i am in cart logged as VAT exempt customer all prices are displayed without tax except this custom fee. Even when i finish order and check order detail as admin i see all items (product, shipping) without VAT but custom fee is still with VAT.

Thanks.