This article joins a somewhat nascent, but growing, body of scholarship addressing the ethical obligation to pay tax. The analysis is grounded to the ethical duty to obey law generally and highlights two competing orientations to statutory interpretation. The norms of self-interested advocacy suggest that tax planners should assert that interpretation that will generate the most wealth for the client. The norms of professional advising, by contrast, direct the tax planner to interpret tax law with reference to plain meaning, interpretive (...) maxims, court precedents, and legislative purpose. When the two orientations differ, the ethical duty to obey law requires the tax planner to recommend, and for the taxpayer to follow, the latter view. Case studies drawn from a Louisiana sales tax avoidance scheme and from Google’s profit-shifting activities illustrate the ethical issues incumbent in tax interpretation. (shrink)