When speaking of the ethics of giving tax advice, whether by a lawyer or an accountant, what often comes to mind concerns the ethics of advising clients as to ways of reducing their tax liability. This necessarily triggers a variety of views, often impacted by individual so-called ‘ethical tolerance’, rather than a concrete principle. This article instead focuses on an ethical domain for tax advisers with an ostensibly more concrete application, namely the application of conflicts of interest rules in tax practice.