This fifth edition covers the basics of the federal income taxation of partnerships and corporations including the taxation of LLCs, LLPs and S corporations. In addition, it alludes to a short list of other business enterprises. We designed the text for teaching in two components: partnerships and corporations. Both components use the traditional "cradle-to-grave" approach. Because of their practical importance, the book refers to Social Security taxes and estate taxes. There is no discussion of State income taxes. Although the book is comparatively short, the materials are thorough and heavily supplemented with problems that are scattered along the way, rather than at the end of each chapter. The problems are not especially difficult. Instead, we designed the problems to build confidence while at the same time forcing students to review the central Code provisions and pertinent regulations. We edited the cases extensively, and eliminated most footnotes as well as the court's and commentators' case and statute citations, without any explicit reference their elimination. Numbered footnotes are from the original materials but, except by accident, they do not retain their original numbering.