The Council adopted a directive allowing member states to implement, on an optional and temporary basis, a reversal of liability for the payment of VAT (value-added tax) on greenhouse gas emission allowance trading (5984/6/10 REV 6 + 6606/10 ADD 1). The aim is to close off certain forms of tax fraud, in particular so-called carousel schemes whereby supplies are traded several times by different suppliers without VAT being paid to the tax authorities.