Aruhn’s research focuses on business taxation and lies at the intersection of accounting, law and economics. He uses archival empirical methods, particularly natural experiments, to examine banking and bank tax outcomes, responses to corporate taxes and tax avoidance and the interaction between law and accounting. For instance, his dissertation exploits variation in state taxation of financial institutions to explore the effects of bank taxes on the intensity and location of corporate investment. Other studies focus on employee responses to media coverage of firm taxes, the disclosure effects of bank taxation, the tax effects of whistleblower laws, corporate tax incidence and the effects of tax code complexity.