This chapter focuses on the accounting for “outside basis” differences. Outside basis differences are differences between the book and tax basis of an investment, such as the stock of a corporation (whether wholly-owned, majority-owned/controlled, or less-than-majority-owned/noncontrolled) or an interest in a partnership. It also addresses unique challenges associated with partnerships, foreign branch operations, foreign corporations that generate US subpart F income, and US taxation of global intangible low-taxed income (GILTI).