No provision of EU law requires the Commission, when ordering the recovery of aid declared incompatible with the internal market, to fix the exact amount of the aid to be recovered. It is sufficient for the Commission’s decision to include information enabling the recipient itself to work out that amount without overmuch difficulty. However, if the Commission decides to order the recovery of a specific amount, it must — pursuant to its obligation to conduct a diligent and impartial examination of the case under Article 108 TFEU — assess, as accurately as the circumstances of the case will allow, the actual value of the benefit received from the aid by the beneficiary. In restoring the situation existing prior to the payment of the aid, the Commission is, on the one hand, obliged to ensure that the real advantage resulting from the aid is eliminated and thus to order recovery of the aid in full. The Commission may not, out of sympathy with the beneficiary, order recovery of an amount which is less than the value of the aid received by the latter. On the other hand, the Commission is not entitled to mark its disapproval of the serious character of the illegality by ordering recovery of an amount in excess of the value of the aid received by the beneficiary.

Thus, in the case of a tax on air transport levied directly on airline operators at a low rate for internal flights, the Commission cannot presume that, in a situation where that tax is deemed to be passed on to passengers and where the economic advantage arising from the application of a reduced national rate may also have been passed on to passengers, the advantage actually obtained and retained by the airlines enjoying that reduction amounts, in all cases, to the amount equal to the difference between the amount of the tax calculated by applying the reduced rate and that calculated by applying the normal rate. In such a case, the advantage actually obtained by the airlines does not necessarily consist in the difference between the two rates, but rather in the possibility of offering more attractive prices to their customers and thereby increasing their turnover. Accordingly, in the case of airlines which have paid the indirect tax at the reduced rate, the Commission must determine the extent to which they have actually passed on to their passengers the economic benefit resulting from the application of the said tax at the lower rate, in order to be able to quantify precisely the advantage which the airlines actually enjoyed. Should it prove impossible to determine exactly, in the decision ordering recovery of the aid, the amounts actually corresponding to the said real advantage, the Commission must confer that task to the national authorities and provide the necessary information in that respect.

In any event, recovering from airlines the amount of the difference between the amount of the tax at the normal rate and that at the reduced rate would not enable reestablishment of the situation which would have prevailed if the operations in question had been carried out without the grant of aid, since it is not possible for airlines retrospectively to recoup from their passengers the said amount per passenger that should have been levied. Recovery of the said amount is not therefore necessary in order to eliminate the distortion of competition caused by the competitive advantage procured by such an aid. On the contrary, recovery of such an amount would risk causing additional distortions of competition, since it could lead to recovering more from airlines more than the advantage they actually enjoyed.

Moreover, the fact that the customers of the airlines subject to the air transport tax are not undertakings, within the meaning of EU law, so that no aid can be recovered in their regard, cannot call into question the obligation on the Commission to identify precisely the beneficiaries of an aid, namely undertakings which have had the actual enjoyment of it, and to limit recovery of the aid to the financial advantages actually flowing from the aid having been placed at their disposal.

(see paras 84-86, 97-99, 105, 115, 122)