Ziering & Esman PLLC is jointly led from New York by Zhanna Ziering and Aaron Esman, advising individuals and businesses in IRS and state tax disputes.

Baker McKenzie has a comprehensive tax controversy offering, handling all phases of dispute resolution, from large-scale IRS audits through to high-profile federal court litigation. The team advises on complex domestic and cross-border tax disputes, drawing on deep experience across contentious and investigatory matters. The practice is led from Washington DC by George Clarke, whose work focuses on governmental litigation, including civil and criminal tax proceedings. In Chicago, Mark Oates is noted for his experience in transfer pricing disputes, valuations, research credit matters, inventory accounting, and civil fraud cases. New York-based Maria Eberle is a key advisor to multinational corporations on complex federal and international tax controversies. In Palo Alto, Duane Webber handles procedural disputes involving insurance tax, consolidated returns, inventory, and tax accounting, while Scott Frewing focuses on offshore account investigations and allegations of tax fraud.

DLA Piper LLP (US) has a comprehensive tax controversy practice handling disputes at the international, federal, state, and local levels. The team advises on civil and criminal tax investigations, administrative proceedings, and litigation before the US Tax Court and federal appellate courts. The practice is led from New York by Ellis Reemer, who is noted for his experience in confidential audits, grand jury investigations, and complex tax litigation. Diana Erbsen brings prior experience from roles at the US Department of Justice and the IRS Advisory Council. Joseph Myszka handles complex tax disputes alongside international tax planning mandates, while Henry Cheng focuses on cross-border tax compliance and controversy matters. Steve Dixon recently joined the team, bringing experience in federal tax disputes. Victoria Gu departed the team in March 2026.

Eversheds Sutherland has a prominent tax controversy practice representing clients in disputes before federal district and appellate courts, state supreme courts, and administrative tribunals nationwide. The team is particularly well known for its strength in state and local tax controversy, including multistate audits and complex constitutional challenges. The practice is led from Washington DC by Robert Chase, who advises on state and local tax planning and high-stakes controversy matters, and Mary Monahan, whose work centers on federal and international tax disputes. In Atlanta, Maria Todorova handles franchise, income, sales and use, and property tax controversies. Jeffrey Friedman, also in DC, is noted for his SALT expertise, particularly involving digital economy transactions, while Atlanta-based Eric Tresh advises highly regulated industries, including telecommunications, cable, and electric utilities.

Latham & Watkins has a strong tax controversy practice and is regularly involved in complex corporate tax disputes, including debt-equity characterization, transfer pricing, employee benefits, and fraud-related matters, often with cross-border dimensions. The team represents clients in IRS audits, administrative appeals, and federal and state criminal tax investigations. The Washington DC-based practice is led by Brian McManus, who focuses on disputes with broader national tax policy implications.  Jean Pawlow advises on digital taxation and international tax controversy matters. Newly promoted partner Eric Konopka concentrates on statutory and administrative issues, as well as tax aspects of bankruptcy proceedings. Miriam L. Fisher retired from the partnership in 2025.

Mayer Brown has a sophisticated tax controversy practice representing clients in high-stakes disputes, including transfer pricing adjustments, partnership taxation controversies, and economic substance challenges. The team regularly handles IRS examinations, administrative appeals, and litigation in federal courts. The practice is jointly led by New York-based Brian Kittle, who advises on transfer pricing disputes, business purpose doctrine matters, and complex partnership controversies, and Chicago-based Thomas Kittle-Kamp, whose work centers on litigation arising from partnership and corporate transactions, including economic substance and transactional recharacterization issues. Also in Chicago, John Hildy represents clients in high-value federal tax disputes and transfer pricing cases. Leah Robinson focuses on capital gains tax litigation, while Joel Williamson advises on leveraged partnership transactions, transfer pricing disputes, and proceedings before the IRS Office of Appeals. Rachel Borden joined from the IRS in August 2025 and concentrates on examinations, administrative appeals, and technical controversy matters.

Skadden, Arps, Slate, Meagher & Flom LLP maintains a preeminent tax controversy practice, handling high-stakes federal and cross-border disputes for corporations, partnerships, estates, individuals, and governmental entities. Its work spans IRS examinations, administrative appeals, and litigation before the US Tax Court and federal courts. The practice is led from Washington DC by Raj Madan, who focuses on complex federal tax controversies and multijurisdictional disputes. Also in DC, Christopher Bowers advises on international tax planning and related controversy matters. Juliana Hunter, promoted to partner in Houston last spring, handles disputes involving consolidated returns, transfer pricing, valuation, bankruptcy-related tax issues, and executive compensation. Nathan Wacker represents clients in federal income tax disputes from audit through trial in DC. Nathaniel Carden, in Chicago, advises life sciences, healthcare, and technology clients on controversy and compliance matters.

Caplin & Drysdale, Chartered has a well-regarded tax controversy practice, handling international tax disputes, FBAR penalty matters, and state and local tax controversies. The team is particularly active in fraud investigations, reportable transaction defense, and professional responsibility proceedings. The practice is led by Scott Michel, who advises on civil and criminal tax controversies, including voluntary disclosures and cross-border investigations, and Charles Ruchelman, who focuses on captive insurance taxation and related disputes. Niles Elber represents clients in IRS examinations, administrative appeals, collections matters, and federal court litigation. Victor Jaramillo advises high-net-worth individuals in complex tax controversy matters, while Leila Carney handles IRS examinations and Office of Professional Responsibility proceedings. Benjamin Eisenstat focuses on economic substance doctrine disputes. Carolyn Schenck joined from the IRS in October 2025, and Mark Matthews retired in January 2025. All team members based in Washington DC unless otherwise stated.

Gibson, Dunn & Crutcher LLP has a sophisticated tax controversy practice handling disputes from IRS examinations and administrative appeals through trial and appellate litigation. The team represents clients across the technology, pharmaceutical and medical device, e-commerce, telecommunications, industrials, and financial services sectors. Sanford Stark leads the Washington DC-based practice and focuses on high-value transfer pricing disputes, foreign tax credit litigation, economic substance challenges, and method of accounting controversies. Saul Mezei advises on transfer pricing, treaty-based disputes, employment tax matters, and nonprofit status controversies at the federal level. Terrell Ussing handles complex domestic and cross-border tax disputes, including valuation and fair market value challenges and business expense deduction cases. Michael Desmond departed the team in February 2025.

Holland & Knight advises on federal, state, and international tax matters, spanning structuring and compliance through to audits, administrative proceedings, and litigation. The team regularly represents clients in complex tax controversies and appellate disputes. The practice is jointly led by Dallas-based Mary McNulty, who handles tax issues arising in bankruptcy proceedings; and William Sharp, who advises on domestic and cross-border tax mandates from the firm’s Atlanta, Tampa, and San Francisco offices. Also in Dallas, Lee Meyercord represents clients in federal tax controversies, including IRS audits and administrative appeals. Christopher Rizek focuses on civil and criminal tax disputes, while Joshua David Odintz advises on tax policy, controversy, and planning matters.

Kirkland & Ellis LLP is active across the tax controversy process, advising clients before audits begin and through IRS examinations, administrative appeals, mediation, competent authority proceedings, and federal and state tax litigation. The team includes Chicago-based Natalie Keller, who is particularly active in transfer pricing audits, APAs and competent authority matters, with experience across sectors including automotive, consumer electronics and life sciences. In Washington DC, David Foster handles a broad mix of partnership audit disputes, energy credit matters, international tax issues and criminal tax exposure. Houston-based Richard Husseini brings strong sector knowledge in energy, oil and gas, and utilities-related tax matters. Also in Houston, Leah Patrick focuses on IRS disputes for large companies and high-net-worth individuals.

Kostelanetz LLP is a leading boutique focused on civil and criminal tax controversy and white-collar defense, regularly repesenting individuals and entities in high-stakes fraud investigations, enforcement actions, IRS examinations, and grand jury proceedings. The practice is jointly steered by Caroline Ciraolo, in Washington DC, a former senior official at the US Department of Justice Tax Division who handles sensitive audits, administrative appeals, and criminal tax prosecutions, and Bryan Skarlatos in New York, who focuses on tax compliance and enforcement disputes, penalty defense, and IRS whistleblower proceedings. Todd Welty leads from Georgia, while Frank Agostino, based in New Jersey, joined in November 2025 and advises on criminal tax defense mandates. Melissa Wiley, Victor Suthammanont, and Karen Kelly  also joined in 2025, and regularly advise on sensitive compliance and internal investigation matters.

The Washington DC-based team at Miller & Chevalier Chartered handles a wide range of domestic and cross-border tax disputes, leveraging team members' government experience to support clients with matters in the federal, distract, and tax courts. Michael Desmond co-heads the practice, a go-to for clients seeking before the IRS and IRS Independent Office of Appeals examination divisions, as well as the US Tax Court and federal courts of appeal. Co-head George Hani has a practice focused on tax controversy resolution at the administrative level, specifically tax accounting matters. Kevin Kenworthy is a key name for litigation, and Lisandra Ortiz is recommended for transfer pricing-related matters.

Akerman LLP has a strong state and local tax controversy practice representing clients in administrative proceedings, trial litigation, and appellate review. The team regularly handles multistate audits, constitutional challenges, and disputes involving evolving interpretations of state tax statutes. Chicago-based David Blum leads the practice and focuses on high-stakes audit defense, cases of first impression, and constitutional challenges to state tax regimes. In Fort Lauderdale, William Sullivan advises on complex SALT controversies. New York-based Stefi George handles disputes arising from aggressive reinterpretations of state tax codes and emerging technology taxation issues, including software-as-a-service, digital services, and marketplace facilitator laws. Jennifer Lindy represents international companies on US tax controversy and related accounting and reporting matters. Brittney Little recently joined the firm, bringing experience in cross-border tax issues and offshore voluntary disclosure programs. Erin Hines joined from Chamberlain Hrdlicka in January 2025.

Baker Botts L.L.P. advises clients in the energy, technology, and financial services sectors on complex federal and state tax controversies. The team handles a range of disputes, including estate, gift, and generation-skipping transfer tax matters before the IRS, particularly those involving sophisticated transfer planning structures and valuation issues. Dallas-based Stephen Marcus is a key member of the group. John Porter represents high-net-worth individuals and businesses in federal tax controversies. Keri Brown focuses on estate, gift, and income tax litigation in Texas. In San Francisco, Jon Feldhammer advises on procedural tax matters, while Houston-based Renn Neilson handles state and local tax disputes.

Chamberlain Hrdlicka has a broad tax controversy practice handling disputes involving income, estate and gift, employment, and excise taxes, as well as matters concerning tax-exempt entities. The team represents clients throughout the controversy lifecycle, from IRS examinations and administrative appeals to federal court litigation, and is led by Philip Karter, based in Philadelphia. In Atlanta, David Aughtry is a seasoned litigator with experience before the US Tax Court, the Eleventh Circuit, and the US Supreme Court. Houston-based Larry Campagna advises on civil and criminal tax disputes, while Tom Cullinan handles significant enforcement matters. John Hackney focuses on complex substantive and procedural tax controversies, including penalty abatement claims, Section 469 passive activity loss disputes, and gift tax valuation matters. Jaime Vasquez in San Antonio is also recommended.

At Davis Polk & Wardwell LLP, the contentious tax team is frequently engaged on disputes involving partnership tax, transfer pricing, cross-border tax issues and the treatment of debt and equity instruments.  The practice also handles matters concerning withholding tax, foreign tax credits, bad debt treatment and the deductibility of takeover and divestiture expenses. New York-based Mario Verdolini heads the team and is regularly instructed in tax litigation, administrative proceedings, ADR and risk management mandates, particularly for clients in the manufacturing, consumer products, media and pharmaceuticals sectors. Also in New York, Christopher Baratta is active in government and internal investigations, with experience spanning transfer pricing disputes and the tax treatment of corporate transactions.

Norton Rose Fulbright advises clients on federal and state tax controversies, including IRS examinations, administrative appeals, summons enforcement actions, and state and local property tax disputes. Led by William Cavanagh in New York, the team represents clients throughout the controversy process, from audit and mediation through to litigation. Houston-based Robert Morris also leads the practice, focusing on federal tax disputes, including IRS audit proceedings and Fast Track mediation. Steve Kuntz handles transactional tax matters, while Richard Hunn advises on white-collar investigations and enforcement-related issues. Robert Phillpott joined from Reed Smith LLP in February 2025 and focuses on corporate tax controversy, and Jeffrey Korenblatt, who joined from Holland & Knight in June 2025, advises on cross-border transactional tax matters.

Steptoe LLP maintains a sophisticated tax controversy practice handling foreign tax credit litigation, international tax disputes, and transfer pricing controversies. Led by Beth Tractenberg, the team also represents clients in matters involving financial products, economic substance doctrine challenges, insurance taxation disputes, and constitutional tax issues, as well as high-profile civil and criminal tax proceedings. Lawrence Hill is a seasoned litigator representing major financial institutions, multinational corporations, and high-net-worth individuals in complex civil and criminal tax controversies. Caitlin Tharp focuses on federal tax controversy matters, including IRS examinations and related litigation.

Vinson & Elkins LLP fields a broad tax controversy practice, covering IRS enforcement, administrative appeals, Fast Track Mediation and contentious transfer pricing works. The practice is jointly led by George Gerachis in Houston, who is regularly engaged in federal and state tax disputes, and Kathleen Pakenham in New York, whose practice centres on partnership tax, valuation, transfer pricing and tax procedure. New York-based Adriana Wirtz adds experience in partnership allocation and basis adjustment issues, debt-equity classification and worthless stock matters. The team is a key contact for clients in the financial services, technology, healthcare, real estate and energy sectors.

BakerHostetler handles the full range of contentious and advisory tax work, spanning federal, state and local tax litigation, audits, appeals and enforcement actions, as well as risk mitigation and compliance matters. The practice is jointly led by Jeffrey Paravano in Washington DC, Michelle Hervey in Cleveland and Elizabeth Smith in New York. Paravano is noted for cross-border tax matters and recent work on Supreme Court proceedings concerning wealth taxes and mark-to-market taxation for high-net-worth individuals. Hervey advises clients across the healthcare, financial services, private equity, aerospace and defence sectors on corporate transactions and high-stakes disputes. Smith is regularly engaged on IRS audits, investigations and litigation, with particular experience acting for hedge funds and private equity clients.

 

Dentons represents clients in federal, state, and local tax controversies, handling matters from audits and administrative proceedings through trial litigation. The team advises on pre-trial preparation, pleadings, discovery, and courtroom proceedings. Louisville-based Mark Loyd handles sales, property, income, and excise tax disputes, including audit defense and administrative protest matters. In Birmingham, Gregory Rhodes serves as trial counsel in federal and state tax litigation. Michelle Levin, based in Huntsville, focuses on IRS audits and administrative appeals. Ronald Levitt in Birmingham advises on business and tax planning matters. Bailey Roese, in Louisville, handles tax litigation and captive insurance taxation issues.

Greenberg Traurig advises on tax planning and controversy matters spanning domestic and cross-border transactions, transfer pricing, and global structuring. The team represents clients in disputes before the Internal Revenue Service and state and local taxing authorities. Michelle Ferreira leads the practice in San Francisco, and counsels individuals, partnerships, estates, and corporations in federal and state tax controversies. In New York, Barbara Kaplan advises domestic and foreign clients in examinations and related litigation, and Scott Fink focuses on civil and criminal federal and state tax disputes. San Francisco-based Bradley Marsh handles a broad spectrum of state and local tax controversies, including sales, documentary transfer, transient occupancy, income, gift, and estate taxes.

Nelson Mullins Riley & Scarborough LLP advises on federal and state tax controversies, including disputes involving transfer pricing, foreign tax credits, research credits, employee retention credits, and conservation easements. The team represents clients throughout the dispute lifecycle, from examinations and administrative appeals to trial and appellate proceedings. The Houston-based practice is jointly led by Juan Vasquez, who handles examinations, appeals, and litigation, and Peter Lowy, a state and local tax specialist with significant experience in the energy sector. David Medina focuses on litigation and appellate matters, drawing on his experience as a former justice of the Texas Supreme Court. Stuart Clements handles controversy and planning matters with an emphasis on captive insurance, while Ranesha Fountain advises on tax planning.

Pillsbury Winthrop Shaw Pittman LLP represents clients in complex tax disputes before the IRS, the US Tax Court, state and local taxing authorities, and appellate tribunals nationwide. Led by Nora Burke, the team handles federal and cross-border controversies, including transfer pricing disputes and individual audit defense matters. Lawrence Sannicadro advises private clients, as well as estates, trusts, and closely held businesses, in tax controversy matters. Jeffrey Vesely, in San Francisco, focuses on state and local tax disputes, including income, franchise, sales and use, and gross receipts taxes. In Sacramento, Carley Roberts represents clients in the energy, technology, telecommunications, retail, and manufacturing sectors. Team members based in New York unless otherwise stated.

Sidley Austin LLP’s tax controversy team handles federal and state tax disputes nationwide, covering audits, administrative appeals and litigation through to the highest appellate levels. The practice is led by Washington DC-based Matthew Lerner, who is active in federal and state tax litigation, including disputes involving transfer pricing, international tax provisions and tax accounting issues. Also in Washington DC, Nathan Clukey handles domestic and cross-border tax disputes, with particular experience in transfer pricing, research credit and tax-related internal investigations.. New York-based Richard Leavy focuses on state and local tax controversies.

White & Case LLP has an established tax controversy practice handling domestic and cross-border civil and criminal tax disputes and investigations. The team represents US and multinational corporations, tax-exempt organizations, and high-net-worth individuals in complex matters, including sensitive enforcement proceedings and large-scale controversies. The practice is jointly led by Kevin Spencer, who joined from McDermott Will & Schulte last year and advises on high-value disputes across sectors including sports, gaming, and technology; and Kim Marie Boylan, who concentrates on IRS administrative appeals, Fast Track settlement procedures, mediation, and other alternative dispute resolution mechanisms. Sean Lyons represents clients in IRS examinations and appeals proceedings. All mentioned team members are based in Washington DC.

The tax controversy team at Winston Taylor handles disputes with the IRS, including examinations and appeals, as well as selected matters before the DOJ Tax Division at both federal and state levels. The practice advises on corporate and partnership tax disputes, internal investigations, criminal tax issues, and multi-jurisdictional matters, supported by a capable e-discovery function. The group is jointly led from Washington DC by James Mastracchio, who advises companies, boards and senior management on civil and criminal tax matters, and Susan Seabrook, whose practice focuses on tax enforcement issues, often with cross-border elements. In New York, Karl Kurzatkowski  concentrates on insurance tax, international tax, and tax controversy matters.

Blank Rome LLP advises on state and local tax planning and controversy matters, including corporate franchise and income tax, sales and use tax, personal income tax, and local business licensing issues. In New York, Mitchell Newmark is leading the group and is focused on trial and appellate tax matters, and Craig Fields advises on the tax aspects of corporate transactions and reorganizations. Nicole Johnson handles franchise, gross receipts, gaming, and sales and use tax matters. Tampa-based Eugene Gibilaro focuses on income, franchise, and unclaimed property issues. New York-based Irwin Slomka is also noted.

Fenwick & West LLP’s contentious tax practice is active in emerging digital asset tax disputes, alongside transfer pricing controversies, APAs, IRS compliance matters and disputes involving inbound multinational companies. The practice is led by Silicon Valley-based Larissa Neumann, who focuses on complex tax structuring. Also in Silicon Valley, Adam Gahtan brings experience in high-stakes patent litigation and appellate work, particularly in the pharmaceutical sector, while David Forst is noted for his work on the taxation of blockchain technology. New York-based Vanessa Park-Thompson is a key contact for life sciences and technology companies, with experience in tax litigation involving deductions for online software.

Moore Tax Law Group represents companies and individual clients in disputes involving corporate and partnership tax issues, foreign tax compliance, and audit and penalty matters affecting high-net-worth individuals. The Chicago-based practice is led by Guinevere Moore, who advises private clients in tax controversy matters. Lauren Darwit handles criminal tax cases, including matters involving charitable contribution issues. Kathy Enstrom focuses on investigation-related matters. Zhanna Ziering and Aaron Esman left to establish Ziering & Esman PLLC in January 2025, and Maha Sadek joined from the IRS in May 2025.

Sullivan & Worcester LLP advises on federal and state tax controversy matters, including administrative proceedings and litigation, alongside international planning and REIT taxation issues. The Boston-based practice is jointly led by Richard Jones, David Nagle, and Daniel Ryan. Jones handles disputes involving corporate nexus, domicile, apportionment, step transaction doctrine, and unitary reporting before state tax authorities, appellate tribunals, and the IRS. Nagle focuses on tax audits, administrative appeals, and state tax planning for complex business transactions. Ryan advises on federal and state tax litigation and related transactional planning involving corporate, franchise, sales and use taxes. Caroline Kupiec represents life sciences and technology clients in tax controversy matters.