(Reference for a preliminary ruling– Article99 of the Rules of Procedure of the Court– Excise duties– Directive 2008/118

37By its second and third questions, which it is appropriate to examine together, the referring court asks, in essence, whether EU law must be interpreted as precluding national authorities from being able to justify their refusal to reimburse an indirect charge that is contrary to Directive 2008/118 by assuming that that charge has been passed on to third parties and, as a result, that the taxable person has been unjustly enriched.

38As follows from settled case-law, the right to a refund of taxes levied in a Member State in breach of EU provisions is the consequence and complement of the rights conferred on individuals by those provisions as interpreted by the Court. A Member State is thus in principle required to repay taxes levied in breach of EU law, in accordance with the applicable national procedural rules and with due regard for the principles of equivalence and effectiveness (see, to that effect, inter alia, judgments of 9November 1983, San Giorgio, 199/82, EU:C:1983:318, paragraph12, and of 1March 2018, Petrotel-Lukoil and Georgescu, C‑76/17, EU:C:2018:139, paragraph32).

39There is only one exception to the obligation to reimburse taxes levied in a Member State in breach of EU provisions. So as not to lead to the unjust enrichment of the persons concerned, the protection of the rights so guaranteed by the EU legal order excludes, as a matter of principle, the repayment of taxes, charges and duties levied in breach of EU law where it is established that the person required to pay such charges has actually passed them on to other persons (see, to that effect, judgments of 14January 1997, Comateb and Others, C‑192/95 to C‑218/95, EU:C:1997:12, paragraph21, and of 1March 2018, Petrotel-Lukoil and Georgescu, C‑76/17, EU:C:2018:139, paragraph33).

40It is therefore for the national authorities and courts to ensure observance of the principle prohibiting unjust enrichment, including where national law is silent.

41In circumstances such as those referred to in paragraph39 of the present order, the burden of the charge levied though not due is borne not by the trader who is subject to it but by the purchaser to whom it has been passed on. Therefore, to repay the trader the amount of the charge already received from the purchaser would be tantamount to paying him or her twice over, which may be described as unjust enrichment, whilst in no way remedying the consequences for the purchaser of the illegality of the charge (see, to that effect, judgments of 14January 1997, Comateb and Others, C‑192/95 to C‑218/95, EU:C:1997:12, paragraph22, and of 1March 2018, Petrotel-Lukoil and Georgescu, C‑76/17, EU:C:2018:139, paragraph34).

42A Member State may, therefore, in the light of EU law,resist repayment of a charge levied though not due only where it is established by the national authorities that the charge has been borne in its entirety by someone other than the taxable person and that reimbursement of the charge would constitute unjust enrichment of the latter. It follows that, if the burden of the charge has been passed on only in part, the national authorities are required to repay only the amount not passed on (see, to that effect, inter alia, judgments of 9November 1983, San Giorgio, 199/82, EU:C:1983:318, paragraph13; of 14January 1997, Comateb and Others, C‑192/95 to C‑218/95, EU:C:1997:12, paragraphs27 and 28; and of 2October 2003, Weber’s Wine World and Others, C‑147/01, EU:C:2003:533, paragraph94).

43As that exception to the principle of reimbursement of taxes which are incompatible with EU law is a restriction of a subjective right derived from the EU legal order, it must be interpreted restrictively, taking account in particular of the fact that passing on a charge to the consumer does not necessarily neutralise the economic effects of the tax on the taxable person (see, to that effect, judgments of 2October 2003, Weber’s Wine World and Others, C‑147/01, EU:C:2003:533, paragraph95, and of 1March 2018, Petrotel-Lukoil and Georgescu, C‑76/17, EU:C:2018:139, paragraph35).

44Even though indirect taxes are designed in national law to be passed on to the final consumer and in commerce are normally passed on in whole or in part, it cannot be generally assumed that the charge is actually passed on in every case. The actual passing on of such taxes, either in whole or in part, depends on various factors in each commercial transaction which distinguish it from other transactions in other contexts. Consequently, the question whether an indirect tax has or has not been passed on in each case is a question of fact to be determined by the national court, which is free to assess the evidence adduced before it (see, to that effect, judgments of 25February 1988, Les Fils de Jules Bianco and Girard, 331/85, 376/85 and 378/85, EU:C:1988:97, paragraph17, and of 2October 2003, Weber’s Wine World and Others, C‑147/01, EU:C:2003:533, paragraph96).

45However, in the case of indirect taxes, it may not be assumed that there is a presumption that they have been passed on and that it is for the taxpayer to prove the contrary. The same applies where the taxpayer has been obliged by the relevant national legislation to incorporate the charge in the cost price of the product concerned. Such a legal obligation does not mean that there is a presumption that the entire charge has been passed on, even where failure to comply with that obligation carries a penalty (judgment of 14January 1997, Comateb and Others, C‑192/95 to C‑218/95, EU:C:1997:12, paragraphs25 and 26).

46EU law thus precludes any presumption or rule of evidence intended to shift to the trader concerned the burden of proving that the charges unduly paid have not been passed on to other persons and to prevent him or her from adducing evidence in order to refute any allegation that the charges have been passed on (judgment of 21September 2000, Michaïlidis, C‑441/98 and C‑442/98, EU:C:2000:479, paragraph42).

47Furthermore, even where it is established that the burden of the charge levied though not due has been passed on to third parties, repayment to the trader of the amount thus passed on does not necessarily entail his or her unjust enrichment, since even where the charge is wholly incorporated in the price, the taxable person may suffer as a result of a fall in the volume of his or her sales (see, to that effect, judgments of 14January 1997, Comateb and Others, C‑192/95 to C‑218/95, EU:C:1997:12, paragraphs29 to 32, and of 6September 2011, Lady and Kid and Others, C‑398/09, EU:C:2011:540, paragraph21).

48In those circumstances, the answer to the second and third questions is that EU law must be interpreted as precluding national authorities from being able to justify their refusal to reimburse an indirect charge that is contrary to Directive 2008/118 by assuming that that charge has been passed on to third parties and, as a result, that the taxable person has been unjustly enriched.