This paper outlines the development and implementation of an online educational intervention designed to enhance moral reasoning in higher level tax students. Before decisions are made about how to behave ethically, cognitive moral reasoning takes place. The importance of education in developing morally sensitive individuals who use principled moral reasoning has been widely acknowledged. The literature contends that moral reasoning might be enhanced through certain forms of intervention studies. An online educational intervention designed to enhance moral reasoning in tax was developed and empirically tested for effectiveness through the use of a pre- and post-test and focus group feedback gathered from students. Students' contributions to ethical discussions were analysed to determine their perceptions of salient issues concerning ethics in tax. This paper will inform future educators and researchers designing effective ethics interventions.