The principles of proportionality and of fiscal neutrality underpinning Council Directive 2006/112/EC do not preclude national legislation that allows the authorities to assess the tax due by a taxpayer presumed to have underdeclared value added tax through an inductive method based on sectoral studies which estimate the likely revenues of certain categories of taxpayer, provided that such legislation is applied in conformity with Articles 47 and 48 of the Charter of Fundamental Rights of the European Union. It is for the referring court to determine whether the concrete application of that legislation in a specific case infringes those principles, having regard to all the circumstances of the main proceedings.