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Mark S. Klein

Partner, Chairman of the Firm
  • New York
  • Florida
  • U.S. Supreme Court

B.S., summa cum laude, State University College at Buffalo

J.D., magna cum laude, University at Buffalo School of Law

Mark, Chairman of the Firm, concentrates in New York State and New York City tax matters. He has more than 35 years of experience with federal, multistate, state and local taxation -- and may be best known for his public speaking on tax topics.

Mark splits his time between the Firm's New York City and Buffalo offices. He has represented numerous Fortune 500 companies in connection with corporate, withholding and sales tax audits as well as dozens of individuals who appear on the Forbes 500 list of wealthiest individuals in the United States in connection with New York income tax inquiries.

Mark taught courses on state taxation and tax practice and procedure for the University at Buffalo School of Management Tax Certificate Program and is a member of The CPA Journal editorial review board. He has written numerous books, articles and treatises on the subject of multistate taxation. He is the general editor of LexisNexis Tax Practice Insights: New York; the editor of New York Tax Highlights; the contributing editor of CCH's Annual Guidebook to New York Taxes; and the co-author of the ABA Sales & Use Tax Desk Book, CCH's New York Residency and Allocation Audit Handbook; New York Sales and Use Tax Answer Book, the New York State Bar Association's Contesting New York Tax Assessments; RIA's New York Tax Handbook and New York City Tax Handbook. He is also a contributor to numerous professional and industry-focused publications.


  • Listed, Best Lawyers in America (Tax Law, Litigation and Controversy -Tax) 2018, 2019
  • Listed, Upstate New York Super Lawyers, 2007 - 2018
  • Who's Who in American Law
  • Martindale-Hubbell, 1998-2018 – highest possible peer review rating in legal ability & ethical standards for twenty years




Professional Associations

  • New York State Tax Appeals Tribunal Advisory Committee
  • Executive Committee of ACE Accounting Society
  • Editorial review board, New York State Society of CPAs' CPA Journal
  • Former chair, Bar Association of Erie County Cooperation with the Accounting Profession Committee
  • American Bar Association Tax Committee
  • New York State Bar Association Tax Committee
  • Former chair, Bar Association of Erie County Tax Committee