"knew, or ought to have known, that transaction was connected with fraud previously committed by the supplier or another trader at an earlier stage in the transaction."
"49. Given that the refusal of the right to deduct in accordance with paragraph 45 of the present judgement is an exception to the application of the fundamental principle constituted by that right, it is for the tax authority to establish, to the requisite legal standard, the objective evidence which allows the conclusion to be drawn that the taxable person knew, or ought to have known that the transaction relied on as the basis for the right to deduct was connected with fraud committed by the supplier or by another trader acting earlier in the chain of this of supply."
"[44] That conclusion in relation to a supply of goods also applies in the case of a supply of services as regards the question whether it may be considered that the taxable person knew or should have known that the supply relied on for entitlement to his rights to deduct was connected with fraud committed by the issuer of the invoice, on the grounds that he had not verified whether the issuer of the invoice had the necessary employees available to be able to supply the services at issue, whether that issuer had fulfilled his obligations as regards declaration of those employees and whether the employees of the issuer and carried out the work at issue. "[45] Consequently, the answer to the third question is that [the directive] must be interpreted as meaning that the fact that a taxable person did not verify whether either a legal relationship existed between the workers employed on a work site and the issuer of the invoice or whether the latter had demonstrated those workers does not constitute an objective factor which demonstrates that the addressee of the invoice knew ought to have known that he was participating in a transaction involving fraudulent evasion of VAT, where the addressee was not in possession of any material justifying the suspicion that irregularities or fraud had been committed within that invoice issuer's sphere of activity. Accordingly the right to deduct may not be refused on that ground where the material and formal conditions laid down by that directive for the exercise of that right are met."
“The test that we apply is accordingly whether a person with the knowledge, skill and experience of the director concerned would have known that the transactions were connected with fraud.”
“If a trader should have known that the only reasonable explanation for the transaction in which he was involved was that it was connected with fraud and if it turns out that the transactions was connected with fraudulent evasion of VAT then he should have known of that fact.”
"traders who take every precaution which could reasonably be required of them to ensure that their transactions are not connected with fraud ... must be able to rely on the legality of those transactions without risk of losing their right to deduct ..."
"[59] In those circumstances, it follows from the case law referred to in paragraphs 53 and 54 of the present judgement, that determination of the measures which may, in a particular case reasonably be required of a taxable person wishing to exercise the right to deduct VAT in order to satisfy himself that his transactions are not connected with fraud committed by a trader at an earlier stage of a transaction depends essentially on the circumstances of that particular case. “[60] It is true that, when there are indications pointing to an infringement or fraud, a reasonable trader could, depending on the circumstances of the case, be obliged to make enquiries about another trader from whom he intends to purchase goods or services in order to ascertain the latter’s trustworthiness."
“Taking these issues together we find they do not point unequivocally to involvement in transaction[s] connected to fraud. But they would raise in the mind of the reasonable businessman serious concerns about such a connection.”