This article analyses the problem of shaping EU tax strategy in the energetic sector. The taxes are an important economic instrument influencing the activity on the common EU energy market. The different tax systems for energetic products in the EU-countries create barriers for more effective allocation of resources and lack of equal competition conditions. The last feature becomes especially important in face of EU aspiration to establish a uniform, competitive energy market. The different taxes can cause that the energy market participants can favour activity on internal markets instead of foreign markets. Those problems gain more meaning in reference to EU electricity market, on which the liberalisation process is most advanced. In some EU countries the energy taxes results in the high level of electricity prices. It doesn't promote the achievement of the one of the main purposes of liberalisation, i.e. the decrease of electricity prices. The differences in tax levels have also negative effect on the clarity of electricity price mechanism and disturb the market competitiveness as result. The results of harmonisation of the internal tax systems in the EU countries will not be the same for each country. They will depend on the current degree of taxation in each country and on the scope of their economies' energy efficiency.