The sixth edition of Understanding Federal Income Taxation is a guide for students studying federal individual income taxation. Adopting material from the authors' casebook, Taxation of Individual Income, now in its twelfth edition, the book is specifically designed for law students using other casebooks who seek supplemental material to assist them in their study of federal individual income taxation. Reflecting the changes made by the Tax Cuts and Jobs Act of 2017, this edition of Understanding Federal Income Taxation consists of forty-two chapters with each chapter addressing a basic topic in individual income taxation, e.g., the definition of "gross income," the exclusion of gain from the sale of a principal residence, business deductions including the Section 199A deduction for qualified business income (added by the 2017 tax legislation), the treatment of capital gains and losses, the taxation of gains from the sale or exchange of real property, and the tax consequences of transfers between spouses and incident to divorce. Each chapter provides a detailed explanation of the interpretation and application of relevant Internal Revenue Code provision(s) and Treasury Regulations as well as summaries of leading cases and administrative rulings. The practical application of these authorities is illustrated in the numerous examples contained in each chapter. Because the provisions of the Internal Revenue Code are necessarily at the heart of tax study, each chapter also includes a part or all of the Code section(s) pertinent to the chapter topic. In summary, the book provides a detailed overview of the principles, policies, and law underlying federal individual income taxation.