The US corporate tax system is broken. A combination of high rates, a dysfunctional international system, and a narrow base lead to distortions in business investment and increased complexity. These are largely unforced errors that could be ameliorated with a reformed business tax system. But the benefits of a reformed business tax system, while meaningful, are not large enough to justify introducing new problems, making existing problems worse, or incurring substantial transition costs. This paper attempts to understand the problems with the current system and the magnitude of the potential benefits of reform—while also weighing these benefits against the potential side effects of reform.