Our Team


CPA, CVGA, Principal, Director

Small & Midsize Businesses
DEPARTMENTS: AccountingAuditConsulting

Dennis Theis, CPA, CVGA, Principal, Director

Dennis is a principal in the Audit and Accounting and Outsourced Solutions departments. He focuses his practice on providing financial statement related services to clients throughout various industries including manufacturing and distribution, nonprofit organizations, and governmental and retail entities. Providing clients with opportunities for improvement is a key goal in each relationship.

Beyond his client service responsibilities, Dennis plays numerous other roles at Maner Costerisan and is an integral part of the firm’s success and execution; for example, he serves as director of the small and midsize businesses niche. Dennis is a member of Maner Costerisan’s Marketing Committee and Education Services Group, and is the leader of the Manufacturing and Distribution Solutions group. He also assists clients in utilizing the additional resources of the BDO Business Resource Network (BRN), which is designed to improve performance by reducing costs and improving technology and operational efficiencies.

Dennis was inspired to go into the accounting field because he recognized that accounting gave a broad perspective on many different facets of business. Dennis attributes his success to always listening to and anticipating client needs, the vast resources of Maner Costerisan and a strong work ethic.

Dennis was raised on a dairy farm in Central Michigan, the youngest of 11 children. He currently resides in Lansing with his wife, Luann, and their three daughters. In his free time, Dennis can usually be found outdoors where he enjoys boating, kayaking and fishing with his family at his cottage. He also likes to run, and play catch and lawn games with his family.

I get excited about helping others reach their potential. Using what I know to produce the best result with our team for our clients is what is most rewarding to me. It has not only stretched me professionally but has provided me great personal satisfaction.

Years of Experience



American Institute of Certified Public Accountants (AICPA)

Michigan Association of Certified Public Accountants (MICPA)


Certified Public Accountant (CPA) – Michigan and Washington, D.C.

Certified Value Growth Advisor (CVGA)