Do the expressions ‘obblighi sostanziali', ‘substantive requirements' and ‘exigences de fond' used by the CJEU in the various language versions of the judgment delivered on 8 May 2008 in Joined Cases C-95/07 and C-96/07 refer, with regard to situations entailing reverse charge VAT, to the requirement to pay VAT or the requirement of assumption of liability for the tax, or to the existence of substantive conditions which justify the imposition of VAT on the taxable person and govern the right to deduct, which is intended to safeguard the principle of VAT neutrality and of a single European system – for example, the presumption that there is an inherent connection between the goods purchased and the business carried on (‘inerenza'), whether VAT may be charged and whether it is totally deductible?

C-590/13