United States securities and exchange commission logo July 28, 2021 Jae A. Evans Chief Executive Officer Isabella Bank Corporation 401 N. Main St. Mt. Pleasant, MI 48858-1649 Re: Isabella Bank Corporation Registration Statement on Form S-4 Filed July 22, 2021 File No. 333-258102 Dear Mr. Evans: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding requests for acceleration. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or absence of action by the staff. Please contact Tonya K. Aldave at (202) 551-3601 with any questions. Sincerely, Division of Corporation Finance Office of Finance cc: Kimberly Baber, Esq.