UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 6, 2025

ISABELLA BANK CORPORATION

(Exact name of registrant as specified in its charter)

Michigan

000-18415

38-2830092

(State or other jurisdiction
of incorporation)

(Commission
File Number)

(IRS Employer
Identification No.)

401 North Main Street

Mt. Pleasant

Michigan

48858-1649

(Address of principal executive offices)

(Zip Code)

Registrant’s telephone number, including area code: (989) 772-9471

Not Applicable

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:


☐			Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)


☐			Soliciting material pursuant to Rule l4a-12 under the Exchange Act (17 CFR 240.l4a-l2)


☐			Pre-commencement communications pursuant to Rule l4d-2(b) under the Exchange Act (17 CFR 240.l4d-2(b))


☐			Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.l3e-4(c))

Securities registered pursuant to Section 12(b) of the Act:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common stock, no par value per share	ISBA	The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).


			Emerging growth company			☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Section 5 - Corporate Governance and Management

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(d) Appointment of Brian Tessin as a Director for Isabella Bank Corporation and Isabella Bank

On October 6, 2025, the Board of Directors of the Corporation appointed Brian Tessin to the Board of Directors of Isabella Bank Corporation and to the Board of Directors of Isabella Bank. Mr. Tessin will serve a term as a director until the Corporation's Annual Meeting of Shareholders in 2026. The Board has determined that Mr. Tessin is an "independent director" within the meaning of applicable rules and regulations of the Securities and Exchange Commission.

The Corporation issued a press release dated October 9, 2025 announcing Mr. Tessin's appointment to the Board of Directors of Isabella Bank Corporation and to the Board of Directors of Isabella Bank.

Section 9 - Financial Statements and Exhibits

Item 9.01 Financial Statements and Exhibits

(d) Exhibits:


Exhibit No.						Description

99.1						Director appointment press release issued October 9 , 2025
104						Cover page interactive data file - the cover page XBRL tags are embedded within the inline XBRL document

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ISABELLA BANK CORPORATION

Dated:

October 9, 2025

By:

/s/ Jerome E. Schwind

Jerome E. Schwind, President & CEO

INDEX TO EXHIBITS


Exhibit No.						Description

99.1						Director appointment press release issued October 9 , 2025
104						Cover page interactive data file - the cover page XBRL tags are embedded within the inline XBRL document

ISABELLA BANK CORP 8-K