European Union – Value added tax. European Union law precluded national legislation, such at that at issue in the main proceedings, under which, where a tax investigation procedure was initiated by a tax authority and where a taxable person was fined for failure to co-operate, the date of the refund of overpaid VAT could be delayed until the formal report on that investigation was delivered to the taxable person and the payment of default interest might be refused even where the duration of the tax investigation procedure was excessive and could not be attributed entirely to the conduct of the taxable person in the main proceedings. The Court of Justice of the European Union so held in a preliminary ruling between Glencore Agriculture Hungary Kft. and the Hungarian tax authorities concerning the payment of default interest relating to the refund of overpaid VAT.