Concepts of equity and fairness are at the heart of tax policy. Yet, for all its populist appeal, tax equity is loosely understood and inconsistently applied. This concept comprises at least three distinct dimensions: horizontal, vertical, and individual equity. The very real tension among these components complicates efforts to craft "fair" tax policy, prompting political debates that invoke the rhetoric of equity without engaging its substance. In the end, however, the standard of equity cannot be ignored for long. Equity will always assert its rightful place as the first and most basic set of principles applied to constitutions and laws.