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Mary McNulty represents taxpayers in IRS audits, appeals, and tax litigation, with emphasis on Federal tax procedural issues and partnership audits. She has significant expertise in partnership tax issues relating to private equity, energy, real estate, and exempt organizations.

Mary is the “go-to attorney for boutique, complicated issues” and “a great controversy lawyer,” according to clients quoted by Chambers USA. She is listed as a “Leading Lawyer” in The Legal 500 US 2020, and has been listed as a “Recommended Attorney” from 2015-2020. In the 2015 edition of The Legal 500 US, she was noted as an “expert in federal tax procedures and partnership tax matters.”

Representative Matters

  • Represents large partnerships and public companies in IRS audits and appeals involving oil and gas and energy tax issues, partnership tax issues, and tax litigation and procedural issues, including statutes of limitations, penalties, and interest
  • Represents an international company in an IRS audit and competent authority proceeding involving transfer pricing issues
  • Represents a tax matters partner in an IRS audit of partnership involving a novel self-employment tax issue
  • Successfully represents large corporations in the Court of Federal Claims and IRS administrative proceedings involving multi-million-dollar interest claims on federal tax deficiencies and refunds
  • Successfully represents families in IRS appeals and litigation in estate and gift tax valuation cases
  • Represents taxpayers in Freedom of Information Act requests, appeals, mediation, and lawsuits
  • Served as special tax counsel in connection with the largest non-financial bankruptcy in U.S. history, with multi-billion-dollar tax issues relating to the bankruptcy restructuring and IRS proposed tax adjustments
  • Prevailed in the U.S. Tax Court on a multi-million-dollar administrative adjustment request for a partnership refund, which involved complex partnership litigation procedural issues
  • Prevailed in the U.S. Tax Court in a case involving determination of the transfer price of Saudi Arabian crude oil, in which the alleged deficiencies totaled billions of dollars; the Fifth Circuit affirmed, and the U.S. Supreme Court declined to hear the case on appeal
  • Prevailed in the Federal Circuit in a case involving the deductibility of payments made to the Agent Orange settlement fund
  • Successfully litigated and defended in federal district courts privilege claims in motions to quash IRS third-party summonses
  • Prevailed in an IRS examination of a public manufacturing company’s acquisition of foreign and domestic assets, partnership interests, and stock
  • Prevailed in a multi-million-dollar offshore voluntary disclosure case
  • Provides tax structuring for general partners of energy funds
  • Represents private foundations, pension plans, and other tax-exempt organizations making oil and gas renewable energy, real estate, and other partnership investments

Honors & Affiliations


  • Most Influential Leaders in North Texas (Law: Tax), D CEO The Dallas 500, 2021
  • The Best Lawyers in America© by Woodward/White Inc. (Litigation & Controversy-Tax, Tax Law), 2006-2021
  • Top 50 Female Attorneys in Texas, Texas Super Lawyers® by Thomson Reuters, 2014-2016, 2018
  • Top 100 Dallas/Fort Worth Region, Texas Super Lawyers® by Thomson Reuters, 2014-2016
  • Top 100 Overall, Texas Super Lawyers® by Thomson Reuters, 2016
  • Dallas Litigation & Controversy – Tax Lawyer of the Year, The Best Lawyers in America® by Woodward/White Inc., 2014, 2016
  • Chambers USA by Chambers and Partners (Tax: Controversy, Tax: Litigation), 2009-2021
  • Leading Lawyer, The Legal 500 United States by Legalease (Tax: U.S. Taxes: Contentious), 2018-2021
  • Recognized Attorney, The Legal 500 United States by Legalease (Tax: Domestic Tax, Tax: Tax Controversy, Tax: U.S. Taxes: Contentious), 2015-2021
  • Texas Super Lawyers® by Thomson Reuters (Tax), 2003-2020
  • Tax Directors Handbook, The Essential Guide to the World’s Premier Tax Law Firms, 2014
  • Best Lawyers in Dallas (Tax: Litigation), D Magazine, 2007-2008, 2011-2015, 2017-2019, 2021
  • Best Business Lawyers in Dallas (Tax), D Magazine, 2009
  • The Best Lawyers in Dallas Under 40, D Magazine, 2002
  • Fellow, American Bar Foundation
  • Fellow, Texas Bar Foundation
  • Thompson & Knight LLP Dallas Office Mentoring Award, 2002
  • Martindale-Hubbell AV Preeminent Rating


  • Member, American Bar Association; Tax Section; Council, 2012-2018; Chair, Committee on Appointments to the Tax Court, 2015-2017, Vice-Chair, 2013-2015, Member, 2007-2019; Nominating Committee, 2007-2010; Committee on Government Submissions, 2007-2015; Chair and Vice-Chair, Court Procedure & Practice Committee, 2001-2007; Advisory Panel, 2006-2011
  • Member, State Bar of Texas; Tax Section; Chair, 2011-2012; Vice-Chair, 2010-2011; Secretary, 2009-2010; Treasurer, 2008-2009; Council, 2005-2008; Nominating Committee, 2013-2016, 2019; Chair, Committee on Government Submissions, 2007-2008; Chair, Energy Tax Committee, 2003-2005
  • Member, Dallas Bar Association; Chair, Tax Section, 2005-2006; Vice President, 2004-2005; Secretary and Treasurer, 2003-2004; Council, 2002-2003
  • Tax Editorial Advisory Board, Law360, 2014-2021
  • Board of Advisors and Department Head, Business Entities, Current Developments, 1999-2015
  • Board of Advisors and Contributors, J. S Corp. Taxation, “Limited Liability Companies,” 1995-1998
  • Board Member, The Family Place, 2017-2020
  • Board Member, Business Council for the Arts, 2014-2020; Secretary, Executive Committee, 2018-2020; Member, Executive Committee, 2014-2017; Chair, Membership Committee, 2014-2017
  • Advisory Board, Booker T. Washington High School for the Performing and Visual Arts, 2011-2014; Executive Committee, 2012-2014; Finance Committee Chair, 2013 -2014
  • Management Committee, Thompson & Knight LLP, 2008-2012, 2019-2020
  • Chair, Finance Committee, Thompson & Knight LLP, 2013-2016
  • Chair, Legal Personnel Committee, Thompson & Knight LLP, 2005-2008
  • Treasurer, Christ the King Parents’ Association Executive Board, 2004-2005
  • U.S. Tax Court Judicial Conference, 2001, 2003, 2007, 2009, 2015, 2018
  • Board of Regents, American College of Tax Counsel, 5th Circuit Regent, 2021
  • Treasurer, American Cancer Society Evergreen Gala, 1993-1995

Education & Admissions


  • J.D., cum laude, SMU Dedman School of Law; Order of the Coif; Assistant Editor-in-Chief, Southwestern Law Journal
  • B.B.A., with highest honors, University of Notre Dame; Beta Gamma Sigma; Beta Alpha Psi


  • Texas
  • Certified Public Accountant, Texas
  • U.S. Ct. of App., Federal Circuit
  • U.S. Ct. of App., Fifth Circuit
  • U.S. Ct. of App., Tenth Circuit
  • U.S. Ct. of Fed. Claims
  • U.S. Dist. Ct., N. Dist. Texas
  • U.S. Supreme Ct.
  • U.S. Tax Ct.