What is the most Avios friendly way of paying my HMRC bill at the end of the month? Unfortunately they don't take Amex and charge 1.4% on MC/Visa (reduced in effect to 0.7% as this will be a tax deductible expense in itself). Should I use a Tesco MC, some other sort of card, or are the fees such that it would be better off just avoiding the charge and buying Avios directly with the money saved?