Mark is Chairman Emeritus of the firm and concentrates his practice in New York State and New York City tax matters. He has more than 40 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.
Mark 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 400 list of wealthiest individuals in the United States. He has also been quoted in dozens of newspapers and periodicals, including The New York Times, The Wall Street Journal, Newsday,TheBoston Globe and the Associated Press. Mark has appeared as a state tax expert on CNBC, CNN and other news outlets.
Mark taught courses in the Tax Certificate Program in the School of Management at the University of Buffalo on state taxation and tax practice and procedure. He is a member of The CPA Journal editorial review board and has written numerous books, articles and treatises on the subject of multistate taxation. Mark is 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 State Tax Assessments, 4th Edition; and CCH's New York Sales and Use Tax. Mark is also a contributor to numerous professional and industry-focused publications.
Hodgson Russ Attorneys Mark Klein, Joseph Endres, and K Craig Reilly present "NYS Budget Bill/Hot Audit Issues" at the NCCPAP 2025 Accounting and Tax Symposium on November 19 & November 20, 2025.
Hodgson Russ Attorney Mark Klein presents "Changing Domicile: Dealing with Tax Mobility" at the AICPA & CIMA National Tax Conference on November 17, 2025.
Hodgson Russ Attorney Mark Klein presents "The SALT Mine: Digging Into the Surprising Application of State & Local Taxes" at the AICPA & CIMA National Tax Conference on November 17, 2025.
Joe, Mark Klein, and Andrew Wright continue their discussion about common tax residency errors, and the panel delves into topics that frequently create unnecessary difficulty in New York State audits. Everything from “country club advice” to errors in the tax return, this episode is a must listen for anyone considering making a move out of state.
Common Tax Residency Traps (Part 1)
Joe is joined by Mark Klein and Andrew Wright to discuss some of the most common errors in the world of tax residency. The panel discussed misconceptions related to changing your residency, such as misunderstanding surrounding the six months and a day test and failing to move near and dear items to your new home. These common mistakes can derail and otherwise carefully planned move for taxpayers who are not careful.
Stupid Sales Tax Rules
Have you ever really looked into some of the distinctions between what makes an item taxable or nontaxable in New York? Well, we have, and some of the rules are just plain outrageous. Joe is joined by Mark Klein, Joe Endres, and Josh Lawrence to discuss some of New York State’s silliest sales tax rules. You’ll be shocked at how the tiniest difference can result in a hefty sales tax bill. The panel shares stories about some of the niche sales tax issues that have come up on audit.
A Brief History of State and Local Tax Part 2
In Episode Two of “State Tax Talks with Joe Tantillo,” Joe and the "Tax Titans", Paul Comeau and Mark Klein, continue their discussion of the development of SALT legal practice.
A Brief History of State and Local Tax
In Episode One of “State Tax Talks with Joe Tantillo,” Joe provides an overview of the development of SALT legal practice, as told by experts, Paul Comeau and Mark Klein (or as we call them, the “Tax Titans”).
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