The purpose of this study is to assess whether the so-called formal legitimate supposes a limit or constitutes a protection mechanism for the confidential own will of the testator. To this end, it is necessary to study the regulation of preterition in its two modalities, intentional and unintentional, to determine its connection with the safeguarding of the material legitimate, as well as weighing whether the legal solution must be the same when the lack of mention of an imposed heir in the will is based on the will of the deceased or derives from an error or forgetfulness at the time of its drafting. The consequences of preterition (this overlooking) differ in the ordinances that regulate an individual legitimate, or by quotas, as in the Spanish Civil Code, and a collective legitimate, where the confidential will of the deceased has greater capacity, as is in the case of the Code of Regional Law of Aragon.