Plante Moran, which is one of the nation’s largest audit, tax, consulting, and wealth management firms, announced that Boston-based accounting and advisory firm Tonneson + Co will join the firm, effective July 1, 2025. This strategic combination marks a major milestone in Plante Moran’s continued expansion along the East Coast and affirms both firms’ commitment to their clients and staff.
Among the most significant 25 accounting firms in Boston, Tonneson + Co has a storied 50-year history providing expert audit, tax, and advisory services. With a dedicated team of over 100 professionals and a service footprint spanning multiple industries and international markets, the firm has built its reputation on a client-first philosophy.
Like Plante Moran, Tonneson + Co is regularly recognized for its emphasis on client service, staff development and community engagement.
Since its founding in 1924, Plante Moran has grown from a single accounting practitioner in a Detroit office to a billion-dollar firm with nearly 4,000 professionals serving clients worldwide.
KEY QUOTES:
“We’re excited to join forces with Plante Moran — a 100-year-old, staunchly independent firm known for its award-winning culture. This partnership allows our combined firms to further enhance the capabilities we offer both clients and staff while preserving the unique culture and relationships that have defined Tonneson and Plante Moran for decades.”
Rick Mastrocola, CEO of Tonneson
“For 100 years, Plante Moran has prioritized long-term stability and client success, which has fueled the firm’s steady growth. Tonneson’s shared values and vision for the future make them an ideal partner. We’re excited to welcome their talented team and expand our presence in Boston.”
Jason Drake, managing partner of Plante Moran
