Amendment to the Isabella Bank Corporation Supplemental Executive Retirement Plan

Interest. As of the last day of each Plan Year, the Company shall credit each Participant’s SERP Account with interest on the Participant’s SERP Account Balance equal to a rate established by the Committee as of the first business day of the Plan Year, compounded annually. Unless changed by the Committee, the interest rate shall be based on Federated Investor's Institutional Money Market Management Fund yield (MMPXX) of the current Plan Year, and shall adjust annually as of the first business day of each Plan Year thereafter.