In response to recent calls on a topic that has garnered the significant interest of many researchers in various disciplines, the social norms approach is used to explain factors that motivate taxpayers to comply with tax laws. Several theories attempt to explain the factors that drive the tax morale of taxpayers. Still, a substantial body of research found that social norms theory could provide an explanation about why some taxpayers might comply with tax laws while others do not. However, studies found mixed findings and relationships, and it is still not clear what factors motivate tax morale. This paper aims to explain the implementation of the social norms approach from previous studies, mainly on the relationship between personal norms, descriptive norms, injunctive norms, subjective norms, and tax morale. This paper presents a review of studies from social norms theoretical lens. The findings reveal that the social norms theory provides a suitable theoretical basis to explore tax morale. Indeed, all the factors until now identified as determinants of tax morale can be categorised as either internalised (personal norms) or externalised (descriptive norms, injunctive norms and subjective norms). The outcome calls for a more nuanced understanding of the effect of internal and external social norms dimensions on tax morale and how these norms emerged from the interactions with others and, consequently, affect tax morale. The significant contribution of this paper is that determining what drives tax morale can greatly assist governments in designing tax policies and their administration, particularly in developing countries where compliance rates are low. This is the first study that adopted the social norms theory to explain the factors that influence tax morale from four different norms taxonomies.

Existing literature stresses the importance of socio-economic factors when aiming to increase the willingness of taxpayers to pay their tax obligations. There have been insufficient studies on socio-psychological factors in tax morale research. This study focuses on trust in tax authorities and tax fairness factors that may explain the reasons why people pay taxes. The purpose of this conceptual review is to analyze and synthesize the theoretical and conceptual frameworks of trust in tax authorities and tax fairness in the tax morale context. Trust in tax authorities refers to the level of confidence taxpayers put in tax authorities based on how well they perform their duties. Tax fairness refers to taxpayers who perceive paying taxes as a fair process in terms of the treatments and benefits they receive for the taxes paid. Tax morale is defined as the intrinsic motivation of taxpayers to pay their fair share of taxes. Using the Social Psychology of Taxation (SPT) and Ibnu Khaldun's Theory of Taxation (IKTK), the interrelationships between trust in tax authorities, tax fairness, and tax morale are critically evaluated and analyzed. The review of relevant tax morale literature is conducted to identify any research gaps, inconsistencies, or ambiguities. It is interesting to note that there were mixed findings in terms of the effect of tax fairness on tax morale. Some studies have demonstrated positive relationships, while others have found negative ones. It has been discovered that taxpayers’ trust in tax administrations would increase if tax authorities treated taxpayers with consideration and respect, applied clear and fair procedures to all taxpayers, and assisted them in meeting their tax obligations. A psychological contract aptly captures the interaction between tax authorities and taxpayers, which will manifest in a willingness to pay taxes. Further investigation needs to be carried out in order to statistically validate the direct and indirect relationships between trust in tax authorities, tax fairness, and tax morale.