In response to the potential threat of global warming many countries are considering cost effective policies to reduce greenhouse gas emissions. In this context much attention has been paid to taxes levied on the carbon content of fuels (carbon taxes), since they are a potentially efficient economic instrument for reducing emissions of CO2, the main greenhouse gas. This paper first reviews the existing structure of fossil fuel prices and taxes and the relationship between energy prices and carbon emissions. It then analyses the economic cost of superimposing carbon taxes on top of current energy taxes. Finally, using a simple energy demand system, tax reform proposals are simulated including restructuring present energy taxation by the average implicit carbon tax and a carbon cum energy tax similar to the EC proposal ...