In this essay, I explore the question of who should determine what an ambiguous tax statute means, the courts or the Department of Treasury. The answer to that question is based on two administrative law doctrines: Chevron and Brand X. Here, I explain why Chevron and Brand X violate the Administrative Procedure Act and are unworkable. Then, using a provision in the tax code, I propose that we return to a standard that is both consistent with the APA and easier to implement: Skidmore.