Background: Tax ethics as people internal motivation to pay tax, can explain people tax compliance. This study aims to examine ethics role in tax compliance decisions.
Method: This research is applied in terms of purpose and correlational in terms of method. The statistical population of the study is the taxpayers of Fars province in 2016. Sampling was done randomly from the statistical population. The necessary information was collected by a questionnaire and analyzed by structural equation modeling.
Results: There is a positive and significant relationship between conscientiousness and ethical justice. There is a positive and significant relationship between conscientiousness and contractism. There is a positive and significant relationship between consequentialism and ethical justice. There is a positive and significant relationship between consequentialism and relativism. There is a positive and significant relationship between ethical justice and tax acceptance behavior. There is a positive and significant relationship between relativism and tax acceptance behavior. There is a positive and significant relationship between contractivism and tax acceptance behavior. In contrast, there is no positive and significant relationship between conscientiousness and relativism, as well as between consequentialism and contractism. In addition, among the three mediating variables of ethical justice, relativism and contractualism, only the variable of ethical justice affects the relationship between conscientiousness and consequentialism with tax acceptance behavior.
Conclusion: Findings indicate that consequentialist and conscientious people have more tax acceptance than relativist and contractual people according to ethical justice which is one of the criteria of moral evaluation.