This document contains regulations relating to the disallowance of deductions and credits for nonresident alien individuals and foreign corporations that fail to file a timely U.S. income tax return. The current regulations permit nonresident aliens and foreign corporations the benefit of deductions and credits only if they timely file a U.S. income tax return in accordance with subtitle F of the Internal Revenue Code, unless the Commissioner waives the filing deadlines. The temporary regulations revise the waiver standard. 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.