Implications of Phase-Outs on Individual Marginal Tax Rates

Abstract

The goal of this paper is to show the behavior of effective marginal tax rates relative to statutory marginal tax rates within the rate structure of the present federal income tax regime. Understanding the behavior of effective marginal rates is important as these rates are a significant component of tax planning and decision making. Statutory marginal tax rates are explicitly stated in published rate schedules. Various deductions, exemptions and credits involved in determining the tax liability are phased out as gross income increases. These restrictions result in effective marginal tax rates that can exceed respective statutory rates. Substantial divergence between effective and statutory rates can occur when multiple phase-out provisions overlap and interact. This study develops an algebraic model using tax return information that converts statutory to effective marginal rates. Policy implications concerning simplifying the effective rate structure are also discussed.