The application of the principle of enhanced derivation represents a matter of strict relevance in a period traditionally dedicated to the closure of financial statements. In particular, the provisions of art. 2, paragraph 1, D.M. n. 48/2009, which provides for the deactivation of paragraphs 1 and 2 of art. 109 of the T.U.I.R. and other provisions for determining taxable income that do not comply with the principle of substance over form. In this context, the accounting representations and the consequent tax effects of uncertain qualification/classification phenomena are analyzed, such as sales with the right of return and transfers based on appraisal contracts.