As the fiscal administrative acts constitute a species of the administrative acts, it is necessary to verify to what extent it is applied the theory of nullity from the administrative law and referring to the former. Given the reality that the taxation statement is an act originating from the taxpayer/payer, but being assimilated to a taxation decision, subject to a subsequent verification, there are also present in the fiscal procedure, as well as in the civil procedural law, two categories of acts: acts issued by the fiscal authorities and acts originating from the debtors of the fiscal obligations. Consequently, for the latter, we will encounter inevitably the vices of unlawfulness specific to the documents drawn up by individuals, arising from non-compliance with the general conditions of validity regarding capacity, the consent (the manifestation of will in the sense of declaring the information necessary to establish the taxable base and of undertaking to fulfil the fiscal obligation), the object of the legal act and its cause. Since the doctrine in fiscal matters, especially the monographs on the fiscal procedural law, does not classify the acts related to this branch of law except according to the criterion of their object, it should be pointed out that, also for fiscal administrative documents, their classification is applicable, according to the criterion of the extent of the legal effects that they produce, into normative fiscal administrative acts and the individual fiscal administrative acts. This classification, used in the administrative law, is justified by the presence of the fiscal administrative acts that contain fiscal normative regulations, such as the orders of the president of the National Agency of Fiscal Administration, of the Minister of Finance and other ministers, with an impact in the field of taxation. Or, undoubtedly, this classification has an impact on the cancellation procedures and on the extent of the effects of the nullity of each of the two classes of fiscal administrative acts. Since the Fiscal Procedure Code contains textual references to the right of appreciation of the tax body, using the terminology of the Code, it must be established whether and to what extent it has substance in fiscal matters. As it was "institutionalized" by the classic authors of administrative law, being opposed to the competence related to the administrative authorities, as giving substance to the competence of appreciation, which establishes the dimension of opportunity in the matter of administrative acts, at least at first sight, the tax authorities do not have the competence to appreciate on the extent of fiscal obligations, established on determined criteria.