This paper represents the very first attempt to employ the data of 5x1000 allocation of personal income tax for the purpose of studying the evolution of social preferences of Italian taxpayers. The 5x1000 initiative encourages voluntary contributions toward the support of public goods and collective resources, by allowing taxpayers to direct 0.5% of their personal income tax to nonprofit organizations and public institutions. Our results indicate a decline in moral universalism, accompanied by a gradual shift in social preferences away from solidaristic concerns, leading individuals to prioritize self-interest over empathy for distant others. In addition, universalistic preferences are predominantly found among middle-income taxpayers. In contrast, both lower- and higher-income groups display more particularistic tendencies. For low-income individuals, particularism often centres on immediate material needs. Among high-income taxpayers, it reflects preferences aligned with lifestyle values, such as the prioritization of leisure and quality of life.