abstract: This study examines determinants of the length of conflict between firms and the Internal Revenue Service (IRS). I hand collect firm disclosures of the number of years open for federal tax purposes to create a proxy for IRS conflict length. Using this proxy, I find evidence that larger firms, firms with more book-tax differences, and firms facing higher IRS attention and audit probabilities are associated with lengthier IRS conflicts. In contrast, firms with higher deferred tax assets, intangibles, return on assets, and firms disclosing participation in the Compliance Assurance Process program are associated with shorter IRS conflicts. Additional analyses show IRS conflict length is positively associated with manager risk preferences and poor tax accounting quality. I also find lengthier IRS conflicts are associated with higher future tax risk and higher audit fees. Tax controversy is becoming increasingly important for firms but remains relatively understudied. I provide empirical evidence on cross-sectional variation in IRS conflict length. / Dissertation/Thesis / Doctoral Dissertation Accountancy 2020