Taxable Income

Abstract

This chapter addresses the starting point of any study on income tax: the definition of income as the base of the tax (the subject matter on which the tax is imposed). First, it discusses the two main concepts of taxable income, the source concept and the accretion concept, and the two main methods countries use to define the tax base, the exclusion (a “global” definition of income) or the inclusion (a “scheduler” definition). The chapter then reviews some of the major problems of defining income in the US income tax system and juxtaposes US solutions against those used by other countries. Finally, it discusses the idea of the realization requirement, which has been described as the “Achilles' heel” of income tax.