The provisions of Sixth Council Directive 77/388/EEC must be interpreted as meaning that the principles established by the Court of Justice of the European Union in Case C-317/94 Elida Gibbs [1996] ECR I-5339 concerning the determination of the taxable amount for VAT purposes do not apply when a travel agent, acting as an intermediary, grants to the final consumer, on the travel agent's own initiative and at his own expense, a price reduction on the principal service provided by the tour operator.