This article discusses the possibility of promoting a fiscal reform which would, at a European level, permit a double dividend to be obtained: the mitigation of CO2 emissions and stimulation of employment creation, In this respect, a CO2/energy tax is considered in the light of financing cuts in social contributions equivalent to 1% of the European GDP, Simulations carried out with six European countries reveal that, under certain conditions, this hypothesis could be verified, even if the net impact on unemployment and CO2 is rather limited.