Mark L. Stone, CPA, MST

Managing Partner

Phoograph of Mark L. Stone, CPA, MST Managing Partner

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Mark L. Stone is the Managing Partner of Sales Tax Defense LLC since 2006. The firm specializes in Sales, Use and Transaction Taxes. Mark’s work as a NY state tax auditor as well as a Tax Manager at several prominent accounting firms over the past 20 years has earned him a reputation as one of the top professionals for multi-state Sales and Use Taxes. He is frequently invited by various organizations to speak on Sales & Use Tax issues, and serves as an Expert witness testifying in tax court on behalf of clients. Mark is an adjunct professor at Long Island University C.W. Post.

Areas of Practice

  • Multi-state Sales and Use Tax consulting
  • Sales and Use Tax audit defense
  • Sales and Use Tax refunds and recovery
  • Complex sales tax planning and research
  • Sales Tax Criminal Defense Assistance
  • Representation before government revenue agencies and auditors
  • Representation as expert witness in Sales and Use Tax court cases
  • Advocating for clients at the Bureau of Conciliation and Mediation Services

Professional Affiliations

  • New York State Society of Certified Public Accountants (NYSSCPA), Member
  • National Conference of CPA Practitioners (NCCPAP), Member
  • Accountant/Attorney Networking Group (AANG), Member
  • Network of Accountants (NOA), Member
  • Turnaround Management Association (TMA), Member
  • American Institute of Certified Public Accountants (AICPA), Past Member

Publication Credits

  • Published columns in various media including Long Island Business News, Beyond the Numbers, Private Investment Forum, New York State Society of CPAs Nassau Chapter Newsletter, Daily News, Long Island Pulse Magazine, Nassau Lawyer
  • Quoted in various media including Crain’s New York Business and Practical Accountant

Speaking Credits

  • New York State Society CPA (NYSSCPA) Nassau Chapter, Half-Day State and Local Tax Update
  • Nassau Bar Association
  • Suffolk Bar Association
  • Chambers of Commerce
  • National Conference of CPA Practitioners (NCCPAP)
  • Network of Accountants (NOA)
  • New York State Independent Accountants (NYSIA)
  • New York Sales and Use Tax for Manufacturers program, Faculty (NBI)
  • The Tax Institute at Long Island University (C.W. Post), Moderator and Speaker
  • Key Speaker, Nassau & Suffolk Chapters Half-Day Federal & State Taxation Conferences
  • Sales Tax Seminars for Various Accounting Firms & Law Firms


  • Masters degree in Taxation (with Honors), C.W. Post, Long Island University 2003
  • Bachelor of Science in Accounting and Information Systems, City University of New York 1992

Interesting Facts About Mark

Mark is active in his community, and is committed to giving his time to local organizations educating businesses on the current sales and use tax laws and regulations. He accomplishes this by speaking at Chambers of Commerce, Bar Associations, and at many CPA and law firms throughout Long Island and New York City. As an adjunct professor, Mark encourages his students to start getting involved in professional organizations such as the Institute of Management Accountants (IMA), National Conference of CPA Practitioners (NCCPAP), Accountant/Attorney Networking Group (AANG), and the New York State Society of Certified Public Accountants (NYSSCPA).

Mark is a staunch supporter of the March of Dimes Foundation. He understands the important work this organization does for pregnancy and baby health, especially since his son was born prematurely. His son is now doing well, and was joined by a sister in 2008. Mark and his children live on Long Island, New York. Mark is also active in his children’s school PTA, coaching his son’s little league team and being a troop leader in his daughters Girl Scout Troop, where he was just recognized as new Troop Leader of the year.