Robert Mahon
Robert Mahon

Robert Mahon

Partner, US Lead, Tax

Seattle

Introduction

Experienced in state and local tax law, Bob helps clients minimize liabilities and manage compliance challenges.

Robert L. Mahon helps clients minimize taxes and comply with state and local tax laws. He represents clients in tax audits, refunds, appeals, and litigation. He also advises clients on tax planning and business transactions. Active in the legal community, Bob is the past president of the Tax Section of the Washington State Bar Association and serves as adjunct professor of state and local tax at the University of Washington School of Law, a position he has held for 25 years. 

Education & credentials

  • University of Washington School of Law, LL.M., Taxation, 1996
  • The University of Iowa College of Law, J.D., with high distinction, 1995
  • Grinnell College, B.A., with honors, 1992
  • Bogle & Gates P.L.L.C., Bellevue, WA, Associate, 1996-1999

Professional recognition

  • Ranked by Chambers USA as “America’s Leading Lawyer” for Tax, 2023-2026

  • Listed in Best Lawyers in America: Tax Law, 2012-2026

  • Named Best Lawyers' Seattle, "Tax Law Lawyer of the Year," 2015, 2018

  • Listed in Washington Law & Politics, "Washington Rising Stars;" Listed as Super Lawyer, 2023-2025

Impact

  • Firmwide Chair, Tax, Benefits, & Compensation Practice, 2017-present
  • Firmwide Chair, State & Local Tax Practice, 2010-present
  • University of Washington School of Law, Adjunct Professor, 1999-present
  • Seattle Metropolitan Chamber of Commerce, Board of Trustees, 2018-present
  • Washington Department of Revenue Business Advisory Council, 2018-present
  • Washington State Bar Association, Tax Section, 1996-present President, 2008-2009 State & Local Tax Committee Chair, 2004-2008 Legislative Committee Chair, 2010-2015 Executive Committee, 2004-present
  • American Bar Association, Tax Section, State and Local Tax Committee, Member, 1996-present Executive Committee, 2011-present ABA Sales & Use Tax Deskbook, Editor-in-Chief, 2011-present Publications Committee, Chair, 2017-present
  • Institute for Professional in Taxation, Member, 2018-present ABA/IPT Advanced Sales/Use Tax Planning Committee, Co-Chair, 2013-present
  • Washington Research Council, Board Member, 2018-present
  • American College of Tax Counsel, Fellow, 2022
  • Journal of Multistate Taxation and Incentives Editor-in-Chief, 2012-2017 Author, U.S. Supreme Court Update column, 2003-2012
  • City of Seattle, Ethics & Elections Commission, Chair, 2009-2012; Commissioner, 2004-2012
  • City of Seattle, Campaign Public Financing Advisory Committee, Member, 2008
  • Montlake Community Club, President, 2005-2006; Trustee, 2004-2008
  • City of Seattle, Public-Private Partnership Panel, City Council Appointee, 2000-2001
  • Northwest Women's Law Center, Legislative Committee, 2000-2006
HomeStreet Inc. v. Washington Department of Revenue

Represented taxpayer in a successful business and occupation tax refund action. 166 Wash. 2d 444, 210 P.3d 297 (2009).

Group Health Cooperative v. City of Seattle

Represented taxpayer in a successful challenge to the application of city business and occupation tax to revenues that were preempted by state and federal law. 146 Wash. App. 80, 189 P.3d 216 (2008).

Community Telecable of Seattle Inc. v. City of Seattle

Represented amicus curiae in support of a successful challenge to the imposition of city utility tax on Internet service. 164 Wash. 2d 35, 186 P.3d 1032 (2008)

City of Seattle v. Visio Corporation

Represented taxpayer in successful administrative appeal of the city's assessment of business and occupation tax on software development activities; represented amicus curiae in opposition to the city's subsequent unsuccessful appeal. 108 Wash. App. 566, 31 P.3d 740 (2001)

Alaska Department of Revenue v. Magella Healthcare Corporation

Represented taxpayer in litigation to obtain alternative income tax apportionment under Alaska's version of Uniform Division of Income Tax Purposes Act (UDITPA) § 18.

Puget Sound Energy Inc. v. Oregon Department of Revenue

Represented taxpayer in litigating and ultimately settling an Oregon property tax dispute.

Tenaska Washington Partners, L.P. v. Washington Department of Revenue

Represented taxpayer in a successful challenge to a public utility tax assessment.

VeriSign Inc. v. Washington Department of Revenue

Represented taxpayer in litigating and ultimately settling a business and occupation tax refund related to the taxation of telecommunications services.

Fresh Express Inc. v. City of Bellevue

Represented taxpayer in litigating and settling a city business and occupation tax refund action.

American Honda Motor Company Inc., Chrysler Motors LLC, and Ford Motor Company v. City of Bremerton

Represented taxpayers in litigating and settling a constitutional challenge to the city's imposition of business and occupation tax on import sales.

Consolidated Food Management Inc. v. Washington Department of Revenue

Represented taxpayer in a successful challenge to retroactive changes in business and occupation tax reporting instructions.

Safeway Inc. v. Takko, et al.

Represented taxpayer in a successful appeal of county personal property tax valuations.

BP Oil Supply Company v. City of Tacoma

Represented taxpayer in a successful nexus challenge to the city's assessment of business and occupation tax.