The article explores the challenges of diminishing the compulsory portion in Russian inheritance law. The article scrutinizes the implementation of Article 1149, Section 4 of the Civil Code of the Russian Federation, which empowers the court to diminish or entirely deny the compulsory portion. The lack of clear definitions of the concepts of “property status” and “reasonable needs” in the law leads to heterogeneous judicial practice and the subjectivity of judges. Legal uncertainty forces the law enforcement officer to re-evaluate the same circumstances each time, which reduces the predictability of judicial acts. Based on the decisions of the courts of 2024-2025, including cases from the Republic of Dagestan, the main criteria used by the courts are highlighted: the income level of the mandatory heir, the availability of other habitable housing, as well as the state of health. The key problems are identified: placing the burden of proof on the heir according to the will, the lack of regulatory guidelines for assessing the “sufficiency” of income, as well as the formal approach of the courts, which often do not examine the real property status of the heir when establishing the fact of disability. In order to unify law enforcement practice, it is proposed to supplement the Resolution of the Plenum of the Supreme Court of the Russian Federation No. 9 with an explanation linking the “reasonableness of needs” with the apparent excess of the income of the mandatory heir over the real needs, as well as with the need of the heir according to the will in inherited property as the only housing or main source of livelihood.