This document contains final regulations that provide guidance under section 987 of the Internal Revenue Code (Code) regarding the determination of the taxable income or loss of a taxpayer with respect to a qualified business unit (QBU) subject to section 987, as well as the timing, amount, character, and source of any section 987 gain or loss. Taxpayers affected by these regulations are corporations and individuals that own QBUs subject to section 987. In addition, published elsewhere in this issue of the Federal Register, temporary and proposed regulations (the temporary regulations) are being issued under section 987 to address aspects of the application of section 987 not addressed in these final regulations.