Income taxation explained in conceptual terms: the idea of “income” (the same taxpayer’s dollars should not be taxed twice or deducted twice); economics (efficiency and welfare); tax fairness (ability to pay); business accounting principles; and the time–value-of–money concept. Virtually all features of the tax system (except certain line–drawing issues) are explained with reference to these central concepts. An easily–understood treatise designed to be used by readers not particularly interested in learning all the technical details. The relevant concepts of accounting, financial theory and economics are introduced only on a “need to know” basis.