Mark Koch

Mark is a Director within GTM’s State and Local (SALT) practice, specializing in tax recovery, current-year compliance, and RAR compliance operations. Mark works to ensure accurate and optimized state income and franchise tax filings. His responsibilities include detailed analysis of state modifications, apportionment, and tax credits to identify tax minimization opportunities.

Mark has 35 years of state income and franchise tax experience from his tenure at DuCharme, McMillen & Associates, Inc. (DMA), prior to the practice joining GTM in 2025. He has generated over $100 million in tax savings for clients across a variety of industries, including financial services, pharmaceuticals, and manufacturing, and has led numerous large-scale projects, including a joint-state amended return and recovery initiative for a Fortune 500 financial institution that resulted in a $9 million tax recovery and a multi-cycle IRS audit support project for a global pharmaceutical company. In another engagement, Mark helped a healthcare and hygiene company realize over $10 million in tax savings, effectively providing funding to more than cover all project compliance fees.

Mark is proficient in all state income and franchise tax, with a particular focus on the tax regulations of Arizona, Illinois, Louisiana, Mississippi, Minnesota, North Carolina, and Pennsylvania. He has regularly presented on state income and franchise tax topics for industry groups such as TEI and COST, with a focus on the state-level impact of federal tax changes.

EDUCATION:
B.B.A. in Accounting with a Dual Focus Major in Real Estate from the University of Cincinnati