This document contains final and temporary regulations under section 6109 relating to taxpayer identifying numbers. The final regulations include a cross reference to the temporary regulations, which provide rules for obtaining and using IRS adoption taxpayer identification numbers. The temporary regulations assist individuals who are in the process of adopting children and wish to claim certain tax benefits with respect to those children. The text of these temporary regulations also serves as the text of the proposed regulations set forth in the notice of proposed rulemaking on this subject in the Proposed Rules section of this issue of the Federal Register.