Sustainability gets higher on the policy agenda of many countries in terms of the UN Sustainable Development Goals. Unethical tax behaviour diminishes the tax system’s sustainability, but paying taxes is necessary if we want to contribute to society. There is a deeper need to understand the factors that influence taxpayers’ perceptions, personal values and personal tax culture. Previous research by the OECD (2013, 2019) using the World Values Survey (WVS) did not provide a sufficient explanation of all the socio-economic factors associated with personal tax culture. As the behaviour of an individual is shaped by a set of values, and values can provide predictive and explanatory power in the analysis of attitudes, opinions and actions by policymakers, it is necessary for them to understand such when proposing tax morale incentives within the institutional pillar. A literature review showed that the research topics on personal tax culture present specific assumptions and gaps. To contribute to this topic, a conceptual model was developed, and the relationship between personal values (conservation/self-enhancement), measured by the widely accepted and recognised Schwartz’s circular model, and personal tax culture was analysed with the aim of formulating recommendations for policymakers. The survey conducted in Slovenia involved 202 respondents. Based on exploratory factor analysis and the performed correlation analysis, empirical research suggests that a relationship between personal values and personal tax culture as the cornerstones of an individual’s tax-compliant behaviour and their attitude towards the ethics of tax evasion is significant. The correlation between personal values and an individual’s attitude towards the tax system is insignificant. By understanding the relationships between individuals’ personal and tax culture values, policymakers can achieve a greater sustainable tax system.