For more than 50 years, Gardiner + Company has proven itself a trusted partner for its clients across the country. We set ourselves apart in a simple but, sadly, rare way—by doing things right. Dedication, steady dependability and quality, experienced people are the pillars on which our company was founded

Our People

When we ask our clients why they work with us, they invariably say it’s because of our people. Every day, in every client interaction, our employees deliver the quality reputation we’ve built for more than a half of a century. When you work with Gardiner + Company, you work with a partner who cares.

  • Dennis Gardiner
    CPA, Managing Partner Meet Dennis
  • Daniel “Mark” Gardiner
    CPA, CFE, Partner Meet Mark


In 1964, Dan Gardiner started providing CPA services for the agribusiness and cooperative industries. As his experience and client list grew, the company became Gardiner & Co. P.C. 2003 was a historic year as it marked the changing of the name to Gardiner Thomsen P.C., to include Dan’s long-time colleague and partner, Dave Thomsen. It was also the year that Dan’s sons, Mark and Dennis, were made partners. When Dave retired in 2018, the company name was officially changed to Gardiner + Company, continuing the legacy Dan created in 1964.


Today, Gardiner + Company operates very much like it did when Dan founded it—through hard work, integrity and common sense. We’ve grown exponentially and we remain on the cutting edge of accounting services, but we still believe in making partnerships with clients, in handshakes and cooperation and in associations that are mutually beneficial. For more than 50 years those have been our driving principles, and they’ll keep driving us for the next 50.

More than 300

years of combined experience

More than 15

clients in top 100 agriculture co-ops

More than 100

co-op clients around the country

Over the years, Community Choice has utilized the expertise of Gardiner + Co for audit engagements, tax preparation and compliance reviews.  In responding to our inquiries, the quality advice Gardiner provides is always timely and well researched.

Erik Sorensen, CFO Community Choice Credit Union

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