Mark L. Stone, CPA, MST

Managing Partner

About Mark

Mark L. Stone, CPA, has been the Managing Partner of Sales Tax Defense LLC since 2006.  The firm specializes in Sales and Use Taxes. Mark’s work as a New York State tax auditor as well as a Tax Manager/Principle at several prominent accounting firms over the past 30 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 holds a master’s degree in taxation, and was also an adjunct tax 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
  • Filing sales and use tax returns for all 50 states
  • Representation before government revenue agencies and auditors
  • Representation as expert witness in Sales and Use Tax court cases
  • Nexus Analysis
  • 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
  • Professional Practice Development Group (PPDG), Member
  • American Institute of Certified Public Accountants (AICPA)
  • Chinese American Society of CPAs (CASCPA)
  • New York Society of Independent Accountants (NYSTAP)
  • Long Island Chapter of Association of Certified Fraud Examiners (LIACFE)
  • Jewish Business Network Long Island (JBN)

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 committed to donating his time to local organizations, and 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 the New York area. As an adjunct professor, Mark encouraged his students to get involved in professional organizations such as the National Conference of CPA Practitioners (NCCPAP), 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, as his son was born prematurely. His son, now 17, is driving and planning for college; Mark also has two daughters 15 and 5, and a ferocious mini-goldendoodle in charge of guarding his daughters. Mark and his children live on Long Island, New York. Mark is also active in Fight for Charity, and his children’s school PTA, including being a class parent.