Sustainability gets higher on the policy agenda of many countries in terms of the UN Sustainable Development Goals, as stated in Transforming our world: the 2030 Agenda for Sustainable Development ^[1]. To achieve all 17 Sustainable Development Goals and 169 targets set in the Agenda, paying taxes is necessary if we want to contribute to society ^[1]. Many public goods and services, including education, health care, social security and tax advantages for climate-friendly products and technologies, are paid for by taxes. Therefore, tax revenues are necessary for governments to be able to ensure a country functions well ^[2].

Sustainability also demands changes in human tax behaviour and corporate tax behaviour, and from this perspective, exploring consumer and individual behaviour ^[3] is gaining importance. Tax aggressiveness, tax avoidance and unethical tax behaviour ^[4] from either companies [5,6]^[5][6] or individuals diminish the tax system’s sustainability ^[7]. Therefore, personal attitudes and personal values towards paying taxes are crucial to collect taxes in a proper and fair way.

The problem of tax sustainability was also elaborated within the framework of the Europe 2020 strategy and the EC Action Plan for fair and simple taxation 2020. To make taxation “fairer, greener and fit for the modern economy, and contributing to long-term, sustainable, inclusive growth” ^[7], new decision support tools for policymakers are required. To identify the institutional and socio-economic factors associated with tax morale, previous research by the OECD [8,9]^[8][9] used the World Values Survey (WVS). Some findings from the WVS (2013, 2019) highlighted a need for further research since not all reasons or results could be sufficiently explained by the OECD. There is a deeper need to understand the factors that influence taxpayers’ perceptions of the tax system. Human resources and institutions of the state have an important role ^[10], as the willingness to pay more taxes can be improved through a better understanding of the interlinks, i.e., relationships between personal values and the personal tax culture of individuals.

Tax system sustainability can be increased through tax morale incentives as a policymaking tool within the institutional pillar measured by the tax sustainable index, an instrument based on a four-pillar tax sustainability concept ^[7]. Thus, if there is a relationship between personal tax culture (tax compliance, tax ethics, tax system) and personal values, such as self-enhancement and conservation, and this relationship is not ethical, policymakers can be made aware thereof, and various tools and measures can be adopted to make personal tax culture and personal values become more ethical. According to the OECD ^[9], in the short term, improving tax morale can be realised through behavioural economic approaches, while in the longer term, more structural changes are needed to build trust and legitimacy among taxpayers.

2. Self-Enhancement, Conservation and Personal Tax Culture

Values can either be understood as a psychological construct or a tool for understanding human behaviour ^[11]. Toth-Nagy et al. ^[12] stated that it is essential to examine the impact on society and the impact of the community on the goals. This also requires knowledge of attitudes, which can be expressed as a set of emotions, beliefs and behaviours towards a specific object, person, thing or event, which are frequently formed as a result of personal experience and can have a significant impact on behaviour ^[12]. Attitude could be influenced by an individual’s or a group’s beliefs, feelings and action tendencies towards objects, ideas and people ^[12]. The behaviour of an individual is shaped by a set of personal values that play an important role in explaining various socio-psychological phenomena ^[13]. An individual’s behaviour is the result of their personal values ^[13], and there is a clear connection between personal values and individual behaviour ^[13]. An individual’s personal values determine what is important to them and what is not ^[13]. Each individual is formed by a set of different personal values, such as generosity, universalism, self-directedness, stimulation, hedonism, achievement, power, security, conformity and tradition, and these differ among individuals according to the level of importance they personally place on each value ^[13]. The values of an individual depend on the environment in which the person lives and on the prevailing social, cultural and economic factors. Personal values play a key role in an individual’s motivation for ethical or unethical behaviour [14,15]^[14][15]. Value effects have been observed in many countries, suggesting that they are not bound to a particular culture and seem to matter for many things and in many places ^[16]. There are a number of scales for measuring a wider range of values [17,18,19]^[17][18][19]; however, some are limited to measuring exclusively personal values ^[20]. Schwartz ^[14] set an important milestone in the research and measurement of personal values with his two-dimensional circular design along two bipolar dimensions—self enhancement (power, achievement and sometimes hedonism) versus self-transcendence (benevolence, universalism) and openness to change (self-direction, stimulation and sometimes hedonism) versus conservation (tradition, security, conformity). Schwartz’s theory ^[14] examined the underlying long-term motivations associated with unethicality and suggested that personal values and their overarching circumplex structure are meaningfully related to and predictive for unethicality. In Feldman’s research ^[15], he demonstrated that the universal structure of personal values predicts unethicality across demographics and cultures—suggesting that cultural differences in the endorsement of values can explain cultural differences in ethicality ^[15]. Unethicality was positively associated with self-enhancement values and negatively associated with conservation values ^[15]. Schwartz’s model of personal values was already used in some past research. The link between personal values defined by Schwartz and sustainable development goals by Toth-Nagy et al. ^[12] shows the differences in the national sustainability policies and the thoughts of the population, thus laying the foundation for the inclusion of public participation and its importance in the strategic plan. The model was used also to find out how religiosity is related to the importance attributed to the values examined by Saroglou et al. ^[21]. Their conclusion was that religious people tend to favour values that promote conservation of the social and individual order (tradition, conformity and to a lesser extent, security) and to dislike values that promote self-enhancement (achievement, power) ^[16]. Miles and Yeh ^[16] discovered that most relationships between social categories and personal values vary across countries. Further, country-specific effects are patterned by cultural regions, supporting the idea that similarities in macro-level influences lead to similarities in how social institutions shape personal values ^[16]. Personal values influence attitude, subjective norms and perceived behavioural control, and tourists’ visiting intentions towards eco-friendly destinations were explored ^[22]. The results show that resultant conservation values have positive relationships with three theory of planned behaviour anchors, i.e., attitude, subjective norms and perceived behavioural control ^[22]. Values have a varying influence on individual behaviour ^[13] and shape culture. Culture is known to be the collective mental programming that distinguishes a group from another group ^[23] and appears in the form of individual behaviour, being common to a certain group of people but not to all individuals ^[24]. It consists of values, norms, beliefs, attitudes and more, forming patterns that distinguish one group of people from another, be it a country, a region, an ethnicity or some other group ^[25]. Culture can be observed at different levels, for example, the national, regional, ethical, gender, generational, social and organisational levels ^[26]. Schumpeter ^[27] was the first to define tax culture. In his definition ^[27], he emphasised the evolutionary nature of tax culture, as taxes go through a period of their economic and psychological suitability ^[28]. He drew parallels between the concept of tax culture and the level of progress and modernity and the rationality of taxes ^[28]. Similarly, Spitaler’s ^[29] concept of tax culture posited that the economic, social, cultural, historical, geographical, psychological and other differences that are present and dominant in a certain country and its society definitely influence the design and functioning of the tax system ^[28]. Tax culture is a multidisciplinary concept that, on the one hand, is revealed through the activity approach, and on the other through the process approach ^[30]. The authors of ^[30] state that tax culture determines the level of knowledge of economic entities in the tax sphere and the degree of confidence of citizens in the state policy. The success of tax collection depends on the mentality of the population ^[30]. In addition to moral and ethical norms, the process of forming a tax culture and the behaviour of taxpayers is influenced by a psychological factor ^[30]. Hofstede ^[23] further studied the mutual ties between national culture and tax culture and designed a model by defining national and tax culture from the perspective of four cultural dimensions: individualism, patriarchy/gender, uncertainty avoidance and influence/power ^[31]. Nerré ^[32] proposed that national tax culture should be comprehensively defined as the entirety of all interacting formal and informal institutions connected with the national tax system and its practical execution, which are historically embedded within the country’s culture, including the dependencies and ties caused by their ongoing interaction. According to Nerré ^[33], the tax code, tax authorities, tax experts and taxpayers all come together to form national tax culture. Chuenjit ^[34] used the term “culture of taxation”, saying that the term appears only rarely in the social science literature, even though it plays an important role in tax systems. The meaning of culture of taxation is closely related to other tax terms, such as tax avoidance, tax evasion, tax compliance and tax morale. It constitutes all phenomena resulting from the relationship between taxpayers and tax collectors in the tax system in the form of symbols, signs and tax policies that make up the tax system ^[34]. Therefore, tax compliance, tax avoidance and tax evasion are a subset of the culture of taxation ^[34]. The meaning of tax culture is not so much debatable at the macro level, since tax culture, according to Nerré ^[33], is the subculture of national culture [23,31]^[23][31] and not well-organised conceptually and defined at the micro level. Personal tax culture at the individual level arises from the tax culture at the macro level (the latter is part of the national culture). At the micro level, which is thre subject of this paper, we searchers defined personal tax culture as the tax-related cultural values of the individual, influencing and shaping the individual’s attitude towards the tax system (or tax legislation in the tax system), their attitude towards tax compliance and their attitude towards the ethics of tax evasion. A narrower field of personal tax culture in relation to the tax system is tax legislation, where individuals directly shape the operation and organisation of the tax culture in each country. Based on that definition, weresearchers measured personal tax culture in the conceptual model using its cornerstones: tax compliance, tax evasion and the tax system. Personal tax culture plays a significant role in determining tax compliance behaviour. Kirchler et al. [35,36]^[35][36] strove to explain tax compliance along two main dimensions, i.e., trust in authorities and power of authorities. Trust captures the generic opinion that tax authorities show benevolence and proceed to ensure societies’ common good, while power of authorities encompasses taxpayers’ perception regarding the capability of tax agents to uncover and penalise tax evasion ^[36]. The ability of a state to raise revenues from citizens in exchange for public goods and services is fundamental for economic progress, and scholars have long invested in understanding the drivers of tax compliance and finding the optimal design for tax institutions ^[37]. Tax noncompliance remains one of the most pressing public policy challenges and, especially in developing and emerging economies, undermines the ability of state authorities to provide goods and services in poverty-sensitive areas such as education and healthcare ^[37]. A number of previous authors suggest that significant cross-cultural differences exist between countries that can affect tax compliance in different ways in these jurisdictions [23,31,38,39]^{[23][31][38][39]}. Vincent ^[37] investigated the effects of multi-layer tax arrangements on tax compliance norms and behaviours of individuals in Latin American and African countries. The empirical findings suggest that assigning taxing rights and discretionary powers on tax administration to subnational governments lowers tendencies of compliance and confirm that intergovernmental tax arrangements matter for understanding tax compliance norms ^[37]. Enhancing trust in authorities results in voluntary compliance, whereas enhancing power of authorities yields enforced compliance ^[36]. Trust in authorities reduces negative emotions and induces voluntary compliance [36,40]^[36][40]. The attention is used to be mainly on reasons why people refuse to pay taxes ^[41]. Measures suggested to ensure tax compliance by this perspective were therefore of traditional economic view, which emphasised what can deter taxpayers from evading taxes ^[41]. Voluntary tax compliance is influenced by the individual’s perception of government accountability, based on equity fairness and gender differences ^[42]. Palil ^[38] measured an individual’s tax compliance behaviour using five factors, namely economic (tax rates, tax audits and perceptions of government spending), institutional (the role of the tax authority, simplicity of the tax returns and administration and probability of detection), social (ethics and attitude, perceptions of equity and fairness, political affiliation and changes to current government policy, referent groups), individual (personal financial constraints, awareness of offences and penalties) and other factors (age, income, level, culture, education, gender). The division into these categories is based on Kirchler ^[43] and Loo ^[44], who approached tax compliance from an interdisciplinary perspective—a wider perspective of tax compliance determinants compared to other researchers ^[38]. Tax knowledge is important and significantly affects tax compliance (in a positive direction), meaning that developing tax knowledge further would probably help to increase tax compliance ^[38]. In addition, further analysis also revealed that gender (positive association, females more compliant), income (positive association, higher income earners more compliant) and age (positive association, older taxpayers more compliant) appear to be significantly correlated with tax compliance behaviour if all respondents have an equal level of tax knowledge ^[38]. Gender egalitarianism is often present in research on typical male and typical female values in relation to tax compliance, but the research findings are not uniform. Some studies confirm that women are more ethically oriented in their actions ^[45], are seen as honest taxpayers ^[46], do business more ethically and have a higher level of tax compliance compared to men ^[45]. However, some studies failed to find gender differences or observed that women were not generally more compliant than men ^[47]. Gender differences also arise from levels of education. Women with higher education are more tolerant of tax evasion than those with lower education, and men with higher education are less tolerant of tax evasion than those with lower education ^[46]. Still, other studies confirmed that individuals with lower education are more opposed to tax evasion than those with higher education ^[48]. There is a negative correlation between education and obligatory tax compliance and a positive correlation between education and voluntary tax compliance ^[49]. Education plays an important role in an individual’s knowledge of tax legislation, as individuals with a higher level of education are expected to have greater and better knowledge of tax legislation and fiscal matters ^[50]. A higher level of education can also be a double-edged sword because, as a result, individuals are aware and familiar with the irregularities carried out by the state ^[50]. Strengthening the general level of fiscal knowledge promotes the level of tax compliance, as positive perception of taxation increases ^[51]. The age of citizens is also significantly correlated with attitudes towards tax evasion. When investigating the effect of age on tax compliance, a positive correlation between age and voluntary tax cooperation was confirmed, as in a possible inspection of younger taxpayers, more tax evasion would be found than among older ones ^[49]. Meanwhile, when studying mandatory tax compliance, it was found that there is no statistically significant correlation with age ^[49]. Studying the impact of gender, age and education on tax compliance behaviour is certainly important, but this research is limited, and their influence will not be further investigated in the presented model. The next important cornerstone of personal tax culture is tax evasion. Tax evasion is a violation of legal provisions because individuals (taxpayers) think rationally that they should benefit from paying taxes ^[52]. Tax evasion is one of the most intractable and serious issues for government ^[53]. Tax evasion may lead to a rise in inequality since the wealthy can more readily evade their taxes ^[54]. Who evades taxes, and how much, matters for both economists and policymakers ^[54]. Tax evasion matters for analysing the effects of governments intervention in the economy; it redistributes the tax burden and affects the costs of raising taxes, which is one of the “bread-and-butter concerns of public economics” ^[54]. Knowing how tax evasion is distributed would help tax authorities, which face tight budget constraints, to better target their enforcement effort ^[54]. The European Commission ^[55] defined tax evasion as illegal arrangements in which the tax liability is hidden or ignored, i.e., taxpayers pay less taxes than they are legally required to pay by not disclosing all income or information to the tax authorities. Tax evasion and tax avoidance have increased with the ever greater globalisation of the economy ^[55]. Chohan ^[56] examined how tax evasion whistleblowing can be used to reduce tax evasion in developing countries. Amoh and Ali-Nakyea ^[57] found that corruption activities lead to an increase in tax evasion behaviour. Recent studies also revealed that certain aspects of corporate governance influence corporate tax avoidance ^[58]. The relationship between tax evasion attitudes and personality traits, as moderated by religiosity and income, in a multi-faith cultural context characterised by a weak tax administration was explored. The results show that conscientiousness is negatively associated with tax evasion attitudes emanating from self-interest ^[58]. Tax evasion has been the subject of a number of studies [51,59,60^{[51][59][60][61]},61], where the authors used both traditional ^[61] and modern approaches to measure tax evasion [61,62,63]^[61][62][63]. However, Hofstede ^[23] was among the first to research the interconnectedness of national culture and related tax culture and tax evasion ^[31]. Beliefs, the values and culture of individuals (taxpayers), social norms and demographics have a similar effect on tax compliance ^[64]. By examining the non-economic, psychological and sociological aspects of tax evasion [35^{[35][39][43][64]},39,43,64], behavioural studies have filled the gap left by studies focusing exclusively on tax evasion from an economic perspective [53,64]^[53][64]. In addition to economic and demographic factors, behavioural factors are increasingly being used to measure tax evasion. Jackson and Milliron ^[65] also included the complexity of the tax system, its fairness, contact or contact with the tax authority, ethics and tax morals. McGee [59,66]^[59][66] analysed an individual’s attitude towards the ethics of tax evasion through the prism of four aspects: the individual’s attitude towards the state, the relationship between the individual and the tax authority, the individual’s attitude towards God and the duty to pay ^[66]. Torgler ^[60] discussed tax evasion from the perspective of public finance, but he also touched on some psychological and philosophical aspects of the issue ^[66]. Consistent with Sidani et al. ^[67] and Khalil and Sidani ^[64], two types of tax evasion attitudes are distinguished: justice of system tax evasion that emanates from perceptions of inequity in the tax system and self-interest tax evasion that is an act of selfishness emanating from the desire to maximise personal benefits ^[58]. The third cornerstone of personal tax culture is the tax system or an individual’s attitude towards the tax system. Motivational postures represent the ways in which individuals position themselves in relation to a regulatory tax authority and are predispositions to compliant or non-compliant conduct ^[68]. Braithwaite ^[69] identified five motivational postures in the taxation context: commitment, capture, resistance, disengagement and game-playing ^[70]. An overall positive orientation to authority reflects commitment and capture. If a taxpayer adopts a commitment posture towards the tax system, it means that they feel a sense of moral obligation to pay their taxes and pay their taxes with good will because they believe paying tax ultimately advantages everyone; even if they may not be happy with the tax system, they see paying taxes as a part of life ^[70]. The tax system fits into the concept of sustainable development as a superstructure that characterises the level of socio-economic and cultural development of the state. The tax culture discipline and behaviour of taxpayers and tax authorities also depend on the efficiency of functioning and interaction of its elements (the tax system, subjects of tax relations and tax legislation) ^[30]. The tax system is the legislative component and the basic element of the fiscal system, which includes all compulsory levies, namely taxes, fees and social contributions, and without an institution to deal with their collection and without an engine to put into operation this system, taxation would be nothing more than new legislation ^[71]. In contrast to these positions, wresearchers also have three postures of defiance: resistance, disengagement and game-playing life ^[70]. Resistance reflects doubts about the intentions of the tax authority to behave cooperatively and benignly towards those it dominates in real life ^[70]. The posture of disengagement also communicates resistance, but here, individuals have moved beyond seeing any point in challenging the authorities ^[70]. They do not care that they are not doing the right thing. The tax authority cannot do anything to them if they choose not to pay their taxes. Game-players enjoy the game of finding the grey areas of tax law and the challenge of minimising tax life ^[70].