This study is the first to examine the relationships among Machiavellianism, social norms and taxpayer intentions to fraudulently overstate their deductions. We theorize and empirically document that (a) high Machiavellian taxpayers report significantly less ethical social norms, suggesting that reported social norms are influenced by cognitive biases such as social projection and Machiavellian cynicism; (b) reported social norms are, in general, significantly associated with tax evasion intentions; (c) social norms partially mediate the relationship between Machiavellianism and evasion intentions. Our findings imply that experimental research that controls for key personality traits such as Machiavellianism will be necessary to test the effectiveness of potential interventions designed to enhance social norms and tax compliance. Our findings also raise questions regarding the validity of certain social norm measures used in recent studies, particularly in the case of high Machiavellians. In contrast to much prior research, gender was not associated with the likelihood of committing tax fraud in our multivariate models, suggesting that the higher levels of tax compliance often associated with females may be eroding.