Capstone Adds Mark Rule & Co. in Montana

Mergers and Acquisitions | December 15, 2025

Capstone Adds Mark Rule & Co. in Montana

Bend, OR-based firm Capstone Accounting and Tax said Dec. 10 that it has brought on Mark Rule & Co., a full-service tax and accounting firm in Butte, MT, that specializes in tax preparation for individuals and business.

Jason Bramwell

Bend, OR-based firm Capstone Accounting and Tax said Dec. 10 that it has brought on Mark Rule & Co., a full-service tax and accounting firm in Butte, MT, that specializes in tax preparation for individuals and business.

Financial terms of the deal weren’t disclosed.

Capstone said the partnership expands its footprint into the growing Montana market and increases the resources available to businesses, individuals, and nonprofits in the region.

Susan Olson

“Their decades of client service experience, long-standing relationships in the Butte community, and commitment to the highest levels of client service align perfectly with our values,” Capstone CEO Susan Olson said in a statement. “Adding Montana to our growing Pacific Northwest and Mountain West footprint was a natural next step for our firm.”

Founded in 1980, Mark Rule & Co. provides clients with tax planning, preparation, and advisory services. 

“We set ourselves apart from our competition by providing our clients with high-quality tax & accounting services, prompt, courteous service, and helpful client support resources,” said Matt Pelletier of Mark Rule & Co.

Mark Rule & Co.’s clients will gain access to Capstone’s broader network of professionals and expanded services, including core tax and accounting services, business valuations, 706 estate planning, state and local tax, research and development, tax planning and advisory, and bookkeeping and payroll services.

In addition, the Mark Rule & Co. team will continue to operate from their current office location.

“This enables an expansion in services for our clients and is an exciting new opportunity for our team,” said Mark Rule of Mark Rule & Co. “Our firm’s joining Capstone ensures clients will continue to receive the personal attention they have come to expect from us, with the added benefits that come with a larger network of offices and service providers.”

Formerly known as Capstone CPAs, Capstone Accounting and Tax locked up an outside investment from San Diego-based private equity firm Seaside Equity Partners last April. Capstone said the outside capital will provide the financial and strategic support needed to accelerate its long-term growth, strengthen client service offerings, and expand its market presence through mergers and acquisitions.

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Founded in 2004, Capstone Accounting and Tax is a full-service accounting firm providing tax, accounting, and advisory services to businesses and individuals.

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