
Detweiler Hershey Partner Group

Shareholder/Managing Partner
Marc Derstein
Driven by results, Marc’s no-nonsense approach means he does not shy away from tough issues. Clients value his strong analytical skills, as well as how he challenges them to make smart decisions.
Marc is active in the Calvary Church of Souderton and was the past board treasurer at the Bridge of Hope BuxMont.
In his spare time, Marc can be found coaching his sons’ sporting events, fishing, golfing or hiking in the mountains.
Certification
- Certified Public Accountant
Education
- B.S. in Accounting from Geneva College
Associations
- Member of AICPA
- Member of PICPA
- Graduate of Indian Valley Chamber of Commerce Community Leadership Institute
- Graduate of The Rainmaker Academy
Experienced In
- Retail
- Manufacturing
- Distribution
- Construction & Real Estate

Shareholder
Bruce Thomas
Bruce has been with Detweiler Hershey since 1985. His attention to detail and quiet demeanor put our clients at ease. His patient approach when addressing complicated issues, like compliance work, has endeared him to many of our non-profit clients in particular. Bruce also served as the past Board Chair at the Indian Creek Foundation.
As the firm’s quality control partner, clients can expect strong technical skills, savvy analysis and a calm approach to problem solving from him.
In his spare time he enjoys traveling, golf, sports, reading and collecting sports related memorabilia. Did we mention he also loves the Pittsburgh Steelers?
Certification
- Certified Public Accountant
Education
- B.S. in Accounting from Eastern Mennonite University
Associations
- Member of AICPA
- Member of PICPA
- Graduate of Indian Valley Chamber of Commerce Community Leadership Institute
- Graduate of The Rainmaker Academy
Experienced In
- Non-Profit
- Manufacturing
- Distribution
- Construction & Real Estate

Partner
Jim Rittenhouse
Jim has been with Detweiler Hershey since 1984. Coming from a farm family in Franconia Township, he is known for his outstanding work with family businesses and knowledge in family farm preservation. Jim offers sound advice, influenced by years of technical training and practical experience.
He currently serves on the Board of Directors at Harleysville Bank, Peace Proclamation Ministries International, and Albanian Christian Education Foundation. Additionally, he serves as the Finance Ministry Chairman for Salford Mennonite Church.
Outside of work, Jim helps to manage the family farm which is now in its seventh generation.
“What I enjoy most about Detweiler Hershey is the variety of customers we interact with and the variety of services we provide.”
-Jim Rittenhouse
CERTIFICATION
- Certified Public Accountant
- Certified Valuation Analyst
- Master Analyst in Financial Forensics
EDUCATION
- B.S. in Accounting from Eastern Mennonite University
ASSOCIATIONS
- Member of AICPA
- Member of PICPA
- National Association of Certified Valuation Analysts
EXPERIENCED IN
- Retail
- Non-Profit
- Education
- Construction & Real Estate

Shareholder
Michael Mazza
Michael’s primary focus is helping clients navigate tax issues and providing business consulting to clients of all sizes. Along with that, he is also in charge of leading the firm’s growing payroll practice. Michael has a strong area of expertise in business consulting, mergers and acquisitions, tax planning and research that make him a valuable asset to the firm.
In his spare time, Michael enjoys spending time with his family, golfing and running.
“Our goal is to be involved in peoples journey, not just their result.”
-Michael Mazza
CERTIFICATION
- Certified Public Accountant
- Masters of Science in Taxation
EDUCATION
- B.S. in Economics from Penn State University.
- M.S.T. from William Howard Taft University
ASSOCIATIONS
- Member of AICPA
- Member of PICPA
- Enterprise Worldwide Member
EXPERIENCED IN
- Retail
- Manufacturing
- Distribution
- Construction & Real Estate

Shareholder
Tracy Voce
Tracy excels at juggling many tasks seamlessly, ensuring smooth operations within our firm and the satisfaction of clients. She oversees a majority of the associates, assists in the firms quality control and works with both individual and business clients. Additionally, Tracy is involved in Detweiler Hershey’s business consulting services, helping clients achieve their goals.
Outside of her professional life, Tracy enjoys spending time with her family and volunteering. She currently serves as the board treasurer for the Keystone Opportunity Center, contributing her financial expertise to support the organization’s mission.
Certification
- Certified Public Accountant
Education
- B.S. in Accounting from DeSales University
Associations
- Member of AICPA
- Member of PICPA
- Graduate of The Rainmaker Academy
Experienced In
- Non-Profit
- Manufacturing
- Distribution
- Construction & Real Estate

Shareholder
Nathan C. Weaver
Nate works with businesses and individuals to address their diverse tax and accounting needs. Known for his organized and efficient approach to work, he takes great pleasure in helping clients understand new concepts, including business transitions, tax strategies and cash flow management.
Out of the office, Nate is involved in his church and serves on the BuxMont Council for Messiah University. He enjoys spending time with family, friends and reading a good book.
Certification
- Certified Public Accountant
Education
- B.S. in Accounting from Messiah College (University)
Associations
- Member of AICPA
- Member of PICPA
- Graduate of The Rainmaker Academy
- Graduate of Leadership Upper Bucks
Experienced In:
- Non-Profit
- Manufacturing
- Construction & Real Estate
Let’s Move Forward Together
Connect with us for an in-depth consultation so we can tailor our solution to your specific needs.