Two of New York State’s major accounting firms, Insero & Co. CPAs (Insero) with offices in Rochester and Corning and Ciaschi, Dietershagen, Little, Mickelson & Company, LLP (CDLM) with offices in Ithaca, Cortland, and Watkins Glen, have signed an agreement to merge as of January 1, 2016. The combined firm will have over 125 employees and will operate under the Insero & Co. name. The merger will strengthen the firm’s position as a top tier public accounting and business consulting firm in Western, Central, and the Southern Tier of New York.

Partner Collage 2

“The combination will expand the service offerings for our clients and the growth potential for our team members in each office location. The client base and team members experience for both firms complement each other so well and allow us to continue our growth strategy while maintaining our promise of the highest standard in everything we do,” said Nancy Catarisano, who will serve as Managing Partner.

Catarisano, Nancy

Nancy Catarisano, Managing Partner

“What excites me about this merger is that both firms provide a full range of accounting, auditing, and tax consultation, planning and preparation services.” said John Dietershagen, who will serve as Office Managing Partner for the Southern Tier locations. “However, with the merger, we can now expand Insero’s Outsource Accounting Services Group to Ithaca, Cortland, and Watkins Glen, and build on CDLM’s government, education, and nonprofit experience into the Rochester marketplace.”

John Dietershagen, CPA

John Dietershagen, Office Managing Partner

The combined firm will provide attest, tax, and consulting services, including outsourced staffing solutions, for middle market, small business, and large multinational companies in the manufacturing, distribution, real estate, not-for-profit, education, government, and employee benefit plan industries. For more information, visit