Dennis was licensed as a CPA in New York in 1987 and began his career with Deloitte in Rochester, New York. After his early years in public accounting, Dennis served in a variety of corporate finance and senior management positions, including Chief Financial Officer of both a private and public company.

In 2008, Dennis returned to the practice of public accountancy with a focus on trust, tax and forensic engagements, including expert witness work relating to partnership disputes, construction defect litigation and probate matters. In 2014, Dennis completed his EJD program at Concord Law School so that he could better serve those attorneys and clients in the trust and forensic arenas while maintaining a significant clientele in individual and corporate tax planning and preparation.