VAT is payable on all fuel supply and there is a special 'red duty' excise rate payable on diesel fuel. The former cost is reclaimed through VAT returns in the normal way so is not actually paid by operators, the latter is paid by operators. In addition, there are a variety of charges made by the electricity industry, which are not classed as taxes, to cover the higher cost of renewable electricity, of maintaining capacity through Gas Turbine plant and so on. They are obligatory and are factored into the delivered price that operators pay. So there is no particularly clear answer to the question. The franchises of course add their estimate of fuel costs into franchise bids and they are then, in effect, paid by DfT etc., so it is arguable that only freight + open access operators are really actually exposed to the cost and taxes involved to power trains.....