Article 193 of Council Directive 2006/112/EC must be interpreted as meaning that the only person liable to pay the value added tax is the taxable person supplying services, where those services were supplied from a fixed establishment located in the Member State in which the value added tax is payable. Article 194 of Directive 2006/112 must be interpreted as not permitting the tax authorities of a Member State to regard as liable for the payment of value added tax the recipient of services supplied from a fixed establishment of the supplier, where both the latter and the recipient of those services are established in the territory of the same Member State, even if that recipient has already paid that tax on the mistaken assumption that the supplier did not have a fixed establishment in that State. The principle of the neutrality of value added tax must be interpreted as precluding a national provision which permits the tax authorities to refuse to grant the supplier of services a refund of the value added tax which the supplier has paid, when the recipient of those services, who has also paid the value added tax in respect of the same services, is refused the right of deduction on the ground that that recipient did not have the corresponding tax document, any adjustment of tax documents being precluded under national law where a definitive tax adjustment notice exists.