What changed in this filing

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Item 9A. Controls and Procedures

2026-03-13 compared with 2025-03-12 · 32 added, 119 removed, 86 unchanged (64% of the section changed)

6 unchanged sentences

Based on this evaluation, we have concluded that there have been no such changes during the quarter ended December 31, 2025.

Management’s Report on Internal Control Over Financial Reporting

We are responsible for the preparation and integrity of our published consolidated financial statements.

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America and, accordingly, include amounts based on judgments and estimates.

We also prepared the other information included in the Annual Report on Form 10-K and are responsible for the accuracy and consistency with the consolidated financial statements.

We are responsible for establishing and maintaining a system of internal control over financial reporting, which is intended to provide reasonable assurance to our management and Board of Directors regarding the reliability of our consolidated financial statements.

The system includes but is not limited to:

• A documented organizational structure and division of responsibility;

• Established policies and procedures, including a code of conduct to foster a strong ethical climate which is communicated throughout our Corporation;

• Internal auditors that monitor the operation of the internal control system and report findings and recommendations to management and the Audit Committee;

• Procedures for taking action in response to an internal audit finding or recommendation;

• Regular reviews of our consolidated financial statements by qualified individuals;

• The careful selection, training and development of our people.

There are inherent limitations in the effectiveness of any system of internal control, including the possibility of human error and the circumvention or overriding of controls.

Also, the effectiveness of an internal control system may change over time.

We have implemented a system of internal control that was designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of consolidated financial statements for external purposes in accordance with generally accepted accounting principles.

We have assessed our internal control system in relation to criteria for effective internal control over financial reporting described in “Internal Control-Integrated Framework ” issued by the Committee of Sponsoring Organizations (2013 framework) of the Treadway Commission.

Based upon these criteria, we believe that, as of December 31, 2024, our system of internal control over financial reporting was effective.

Our independent registered public accounting firm, Rehmann Robson LLC ("Rehmann"), has audited our 2024 consolidated financial statements and our internal control over financial reporting as of December 31, 2024.

Rehmann was given unrestricted access to all financial records and related data, including minutes of all meetings of stockholders, the Board of Directors and committees of the Board of Directors.

Rehmann has issued an unqualified audit opinion on our 2024

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consolidated financial statements and an unqualified opinion on the effectiveness of our internal controls as of December 31, 2024, as a result of the integrated audit.

Isabella Bank Corporation

/s/ Jerome E.

President and Chief Executive Officer

(Principal Executive Officer)

March 12, 2025

/s/ William M.

Chief Financial Officer

(Principal Financial Officer)

March 12, 2025

Other Information.

3 unchanged sentences

Not applicable.

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Directors, Executive Officers and Corporate Governance.

For information concerning our directors and certain executive officers, see “Election of Directors” and “Delinquent Section 16(a) Reports” in our Proxy Statement for the Annual Meeting of Shareholders to be held May 6, 2025 (“Proxy Statement”) which is incorporated herein by reference.

For Information concerning our Audit Committee financial experts, see “Committees of the Board of Directors and Meeting Attendance” in the Proxy Statement which is incorporated herein by reference.

We have adopted a Code of Conduct and Business Ethics that applies to the principal executive officer, the principal financial officer and the principal accounting officer or controller of the Corporation.

We shall provide to any person without charge upon request, a copy of our Code of Conduct and Business Ethics.

Written requests should be sent to:

Secretary, Isabella Bank Corporation, 401 North Main Street, Mount Pleasant, Michigan 48858.

We have an insider trading policy governing the purchase, sale and other disposition of the Corporation’s common stock that applies to the Corporation’s directors, executive officers and specifically designated individuals of the Corporation and the Bank as determined from time to time by the Corporation’s Board of Directors.

We believe that our insider trading policy is reasonably designed to promote compliance with insider trading laws, rules and regulations.

A copy of the Corporation’s insider trading policy is filed as Exhibit 19 to this Annual Report on Form 10-K.

We incorporate by reference the information responsive to this Item appearing in our Definitive Proxy Statement for the 2026 Annual Meeting of Shareholders (the “2026 Proxy Statement”), which will be filed no later than 120 days after December 31, 2025.

Executive Compensation.

For information concerning executive compensation, see “Executive Officers” in the Proxy Statement which is incorporated herein by reference.

We incorporate by reference the information responsive to this Item appearing in our 2026 Proxy Statement, which will be filed no later than 120 days after December 31, 2025.

Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

For information concerning the security ownership of certain owners and management, see “Security Ownership of Certain Beneficial Owners and Management” in the Proxy Statement which is incorporated herein by reference.

Equity Compensation Plan Information

The following table provides information as of December 31, 2024, with respect to compensation plans under which our common shares are authorized for issuance to directors, officers or employees in exchange for consideration in the form of goods or services.

Plan Category Number of Securities

Upon Exercise of

Options, Warrants,

(A) Weighted Average

Exercise Price

of Outstanding

Options, Warrants,

(B) Number of Securities

Available for Future

Issuance Under Equity

Compensation Plans

(Excluding Securities

Reflected in Column (A))

Equity compensation plans approved by shareholders:

Equity compensation plans not approved by shareholders:

Deferred director compensation plan (1)

101,493 (3) — (5) — (6)

Restricted Stock Plan (2)

14,733 (4) — (5) — (6)

Total 116,226

(1) Pursuant to the terms of the Directors Plan, our directors are required to invest at least 25% of their board fees in our common stock.

These stock investments can be made either through deferred fees or through the purchase of shares through the Dividend Reinvestment Plan.

Deferred fees, under the Directors Plan, are converted on a quarterly basis into stock units of our common stock based on the fair value of a share of our common stock as of the relevant valuation date.

Stock units credited to a participant’s account are eligible for stock and cash dividends as declared.

Dividend Reinvestment Plan shares are purchased pursuant to the Dividend Reinvestment Plan.

Distribution of deferred fees from the Directors Plan occurs when the participant retires from the Board of Directors or upon the occurrence of certain other events.

The participant is eligible to receive a distribution in the form of shares of our common stock of all of the stock units that are then in his or her account, and any unconverted cash will be converted to and rounded up to whole shares of stock and distributed, as well.

The Directors Plan does not allow for cash settlement, and therefore, such

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share-based payment awards qualify for classification as equity.

We may use authorized but unissued shares or purchase shares of common stock on the open market to meet our obligations under the Directors Plan.

(2) The RSP is an equity-based bonus plan.

Under the plan, we may award restricted stock bonuses to eligible employees on an annual basis that are not fully transferable.

Currently, the eligible employees are Isabella Bank's CEO, President, and CFO.

The RSP authorizes the issuance of unvested restricted stock to an eligible employee with a maximum award ranging from 25% to 40% of the employee’s annual salary, on a calendar year basis.

The employee must also satisfy the annual performance targets and measures established by the Board of Directors.

If these grant conditions are not satisfied, then the award of restricted shares will lapse or be adjusted appropriately, at the discretion of the Board of Directors.

Awards are converted to shares upon payment to the participant based on the market value of our common stock on the date of award.

(3) As of December 31, 2024, the Directors Plan had 101,493 shares eligible to be distributed under the Directors Plan.

The Rabbi Trust holds 142,535 shares for the benefit of participants pursuant to the Directors Plan.

(4) This amount includes shares subject to outstanding stock awards at the maximum amount of shares issuable under such awards.

However, payout of incentive awards is contingent on the individual and the Corporation reaching certain levels of performance.

If the performance criteria for these awards are not fully satisfied, the award recipient will receive less than the maximum number of shares eligible under these grants and may receive nothing from these grants.

Additionally, this amount assumes the closing price of our common stock as of the award grant dates for purposes of the conversion from awards to common stock.

(5) The Directors Plan and the RSP do not have an exercise price.

(6) There is no maximum number of shares available for issuance under the Directors Plan and the RSP has a maximum number of 100,000 shares.

We incorporate by reference the information responsive to this Item appearing in our 2026 Proxy Statement, which will be filed no later than 120 days after December 31, 2025.

Certain Relationships and Related Transactions, and Director Independence.

For information, see “Indebtedness of and Transactions with Management” and “Election of Directors” in the Proxy Statement, which is incorporated herein by reference.

We incorporate by reference the information responsive to this Item appearing in our 2026 Proxy Statement, which will be filed no later than 120 days after December 31, 2025.

Principal Accountant Fees and Services.

For information concerning our principal accountant fees and services see “Fees for Professional Services Provided by Rehmann” and “Pre-Approval Policies and Procedures” in our Proxy Statement which is incorporated herein by reference.

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We incorporate by reference the information responsive to this Item appearing in our 2026 Proxy Statement, which will be filed no later than 120 days after December 31, 2025.

Exhibit and Financial Statement Schedules.

1 unchanged sentence

The following documents are filed as part of Item 8 of this report:

Report of Independent Registered Public Accounting Firm, Plante & Moran, PLLC (PCAOB ID:

Report of Independent Registered Public Accounting Firm, Rehmann Robson LLC (PCAOB ID:

14 unchanged sentences

Amendment to the Articles of Incorporation ( 5 )

Amended Bylaws (5)

Amendment to Bylaws (6)

Amendment to Bylaws (9)

Amendment to Bylaws (10)

Indenture, dated as of June 2, 2021, by and between Isabella Bank Corporation and UMB Bank, National Association, as trustee (1 4 )

Second Amended and Restated Bylaws, as amended on September 24, 2025 ( 6 )

Indenture, dated June 2, 2021, by and between Isabella Bank Corporation and UMB Bank, National Association, as trustee ( 7 )

Form of 3.25% Fixed to Floating Rate Subordinated Note due 2031 (8)

2 unchanged sentences

Isabella Bank Corporation Split Dollar Plan* ( 11 )

Isabella Bank Corporation Supplemental Executive Retirem ent Plan* (13)

Second Amended and Restated I sabella Bank Corporation Supplemental Executive Retirement Plan , as am ended on January 1, 2025 * (1 2 )

Isabella Bank Corporation Restricted Stock Plan* (1 3 )

Isabella Bank Corporation Executive Cash Incentive Plan* (1 4 )

Isabella Bank Corporation Executive Clawback Polic y* (13)

Isabella Bank Corporation Executive Clawback Policy* (1 5 )

Form of Subordinated Note Purchase Agreement, dated as of June 2, 2021, by and among the Corporation and the several Purchasers (16)

Form of Registration Rights Agreement, dated as of June 2, 2021, by and among the Corporation and the several Purchasers (17)

Isabella Bank Corporation Directors and Executive Officers Operating Policy on Trading in ISBA Common Stock

Isabella Bank Corporation Directors and Executive Officers Operating Policy o n Trading in ISBA Common Stock (1 8 )

Subsidiaries of the Registrant

Consent of Rehmann Robson LLC, Independent Registered Public Accounting Firm

Consent of Plante & Moran, PLLC, Independent Registered Public Accounting Firm

Certification pursuant to section 302 of the Sarbanes-Oxley Act of 2002 by the Chief Executive Officer

1 unchanged sentence

Section 1350 Certification of Chief Executive Officer and Chief Financial Officer

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101.INS XBRL Interactive Data File**

7 unchanged sentences

** As provided by Rule 406T in Regulation S-T, this information is furnished and not filed for purposes of Sections 11 and 12 of the Securities Act of 1933 and Section 18 of the Exchange Act

(1) Previously filed as an Exhibit to the Isabella Bank Corporation Form 10-K, filed March 12, 1991, and incorporated herein by reference

(1) Previously filed as Exhibit 3(d) to of the Corporation’s Annual Report on Form 10-K filed with the SEC on March 27, 2001, and incorporated herein by reference.

(2) Previously filed as an Exhibit to the Isabella Bank Corporation Form 10-K, filed March 26, 1994, and incorporated herein by reference.

(3) Previously filed as an Exhibit to Isabella Bank Corporation Form 10-K, filed March 22, 2000, and incorporated herein by reference.

(4) Previously filed as an Exhibit to Isabella Bank Corporation Form 10-K, filed March 27, 2001, and incorporated herein by reference.

(5) Previously filed as an Exhibit to Isabella Bank Corporation Form 10-K, filed March 16, 2005, and incorporated herein by reference.

(6) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed November 22, 2006, and incorporated herein by reference.

(7) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed May 16, 2008, and incorporated herein by reference.

(8) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed March 13, 2019, and incorporated herein by reference.

(9) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed August 28, 2009, and incorporated herein by reference.

(10) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed December 23, 2009, and incorporated herein by reference.

(11) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed December 19, 2008, and incorporated herein by reference.

(12) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed March 31, 2015, and incorporated herein by reference.

(13) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed April 1, 2024, and incorporated herein by reference.

(14) Previously filed as an Exhibit to Isabella Bank Corporation Form 8-K, filed June 2, 2021, and incorporated herein by reference.

(4) Previously filed as Exhibit 3(d) to of the Corporation’s Annual Report on Form 10-K filed with the SEC on March 27, 2001, and incorporated herein by reference.

(5) Previously filed as Exhibit 3.1 of the Corporation’s Current Report on Form 8-K filed with the SEC on May 16, 2008, and incorporated herein by reference.

(6) Previously filed as Exhibit 3.1 of the Corporation’s Current Report on Form 8-K filed with the SEC on September 30, 2025, and incorporated herein by reference.

(7) Previously filed as Exhibit 4.1 to the Corporation’s Current Report on Form 8-K filed with the SEC on June 2, 2021, and incorporated herein by reference.

(8) Included as Exhibit A-1 to the Indenture incorporated herein by reference as Exhibit 4.1 hereto.

(9) Previously filed as Exhibit 10.1 of the Corporation’s Current Report on Form 8-K filed with the SEC on March 13, 2019, and incorporated herein by reference.

(10) Previously filed as Exhibit 10.1 of the Corporation’s Current Report on Form 8-K filed with the SEC on December 19, 2008, and incorporated herein by reference.

(11) Previously filed as Exhibit 10.1 of the Corporation’s Current Report on Form 8-K filed with the SEC on March 31, 2015, and incorporated herein by reference.

(12) Previously filed as Exhibit 10.2 of the Corporation’s Current Report on Form 8-K filed with the SEC on April 7, 2025, and incorporated herein by reference.

(13) Previously filed as Exhibit 10.6 of the Corporation’s Current Report on Form 8-K filed with the SEC on April 1, 2024, and incorporated herein by reference.

(14) Previously filed as Exhibit 10.5 of the Corporation’s Current Report Form 8-K filed with the SEC on April 1, 2024, and incorporated herein by reference.

(15) Previously filed as Exhibit 10.1 to the Corporation’s Current Report on Form 8-K filed with the SEC on April 1, 2024, and incorporated herein by reference.

(16) Previously filed as Exhibit 10.1 to the Corporation’s Current Report on Form 8-K filed with the SEC on June 2, 2021, and incorporated herein by reference.

(17) Previously filed as an Exhibit 10.2 to the Corporation’s Current Report on Form 8-K filed with the SEC on June 2, 2021, and incorporated herein by reference.

(18) Previously filed as an Exhibit 19 to the Corporation’s Annual Report on Form 10-K filed with the SEC on March 13, 2025, and incorporated herein by reference.

Form 10-K Summary.

Not applicable.

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Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

8 unchanged sentences

Barnes Director March 13, 2026

Behen Director March 13, 2026

/s/ Jill Bourland Director March 13, 2026

7 unchanged sentences

Opperman Director March 13, 2026

Payton Director March 12, 2025

/s/ Gerald J.

Ritzert Chief Financial Officer (Principal Financial Officer) March 13, 2026

Rupp Director March 13, 2026

Sackett Director March 13, 2026

/s/ William M.

Schaefer Chief Financial Officer (Principal Financial Officer) March 12, 2025

/s/ Jerome E.

1 unchanged sentence

(Principal Executive Officer), and Director March 13, 2026

Tessin Director March 13, 2026

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 9A. Controls and Procedures