Tax expenditures -- special exemptions and exclusions, credits, deductions, deferrals, and preferential tax rates claimed by corporations, individuals, or both -- support federal policy goals but result in revenue forgone by the federal government. Congress and the administration are reexamining tax expenditures used by corporations as part of corporate tax reform. This book describes trends in the number of corporate tax expenditures and estimated corporate revenue losses since 1986; describes the use of corporate tax expenditures in 2011; and compares the size of corporate tax expenditures to federal spending by budget function and, for tax expenditures used only by corporations, identifies spending programs with similar purposes. This book also uses GAO's tax expenditures evaluation guide to determine what is known about the deferral of income for controlled foreign corporations; deferred taxes for certain financial firms on income earned overseas; and the graduated corporate income tax rate.