A Note on Horizontal Equity

Richard Musgrave has recently offered a new defense of the concept of horizontal equity (HE)—the requirement of equal treatment of equals—as an independent norm in assessing tax policy. This defense is significantly more elaborate than the brief sketch he offered in his pioneering treatise or in his subsequent work on the subject. Musgrave's latest contribution is important because prior literature developing and applying HE measures gives little justification for this norm. The gap in the literature remains, however, because Musgrave assumes what must be demonstrated and suggests an index of HE that is implausible.