The study aims to determine the effect of Machiavellianism, perception of the importance of ethics and social responsibility, ethical considerations and experience toward ethical decision making by tax consultants. Ethical decision making by tax consultants is very important so that when carrying out their work, tax consultants make decisions based on the tax consultant’s code of ethics to encourage tax revenues. The object in this research are registered tax consultants located in Jakarta and Banten. A total of 157 questionnaires were distributes for this research, but only 101 questionnaires could be processed in this research using multiple linear regression methods. The result in this research were Machiavellianism had a negative significant effect on ethical decision making by tax consultant, while perception of the importance of ethics and social responsibility, ethical considerations, and experience had positive significant effect on ethical decision making by tax consultant.