About Us

Mark W. Sullivan, EA, the founder of Sullivan Consulting, entered private practice in St. Louis, MO, in 1998. In 2020, he made a strategic move to the thriving business environment of Scottsdale, AZ. Mark specializes in the intricate realm of federal tax controversy representation, appeals, and consulting, catering not only to individuals and businesses but also extending his expertise to renowned law and accounting firms nationwide.

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Mark's distinguished career includes serving as a consulting and expert witness in a multitude of civil and criminal cases, spanning several federal district courts. His credentials are underscored by an unlimited Enrolled Agents license, a testament to his exceptional knowledge and unwavering commitment to his craft. His recognition by the Internal Revenue Service for admission to practice is grounded in his extensive background as a Revenue Officer, having worked in demanding locations such as New York, NY, St. Louis, MO, and Washington, D.C.

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Mark's extensive experience as a Revenue Officer has uniquely positioned him to navigate the intricate landscape of federal tax matters. Now, based in Scottsdale, AZ, Mark continues to offer his expertise to clients across the nation, ensuring that their interests are diligently and professionally represented.