We examine whether Delaware is a domestic tax haven. We find that taxes play an economically important role in determining whether U.S. firms locate subsidiaries in Delaware and that a Delaware-based state tax avoidance strategy lowers state effective tax rates by between 0.7 and 1.1 percentage points, on average. The tax savings represent a 15-24% decrease in the state income tax burden and translate to an increase in net income of 1.04-1.47%. However, we find that the tax benefits of Delaware tax strategies are diminishing over time in response to initiatives by state governments to limit multistate tax avoidance. (C) 2013 Elsevier B.V. All rights reserved.