This document contains final regulations modifying regulations relating to IRS administrative proceedings to reflect limitations that are required by the enactment of the Taxpayer First Act of 2019. These final regulations implement new rules regarding the persons who may be provided books, papers, records, or other data obtained pursuant to section 7602 of the Internal Revenue Code (Code) for the sole purpose of providing expert evaluation and assistance to the IRS, and adopt further limitations on the types of non-governmental attorneys to whom, under the authority of section 6103(n) of the Code, any books, papers, records, or other data obtained pursuant to section 7602 may be provided. These final regulations also prohibit any IRS contractors from asking substantive questions of a summoned witness under oath or asking a summoned person's representative to clarify an objection or assertion of privilege. The regulations affect persons who are examined by the IRS and any persons who are questioned by the IRS under oath pursuant to section 7602.