Marathon Bancorp, Inc. /MD/

To the Board of Directors and

Stockholders of Marathon Bancorp, Inc.

Wausau, Wisconsin

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of Marathon Bancorp, Inc. (the “Company”) as of June 30, 2026 and 2025, and the related consolidated statements of income, comprehensive income, changes in stockholders’ equity, and cash flows for each of the years in the two-year period ended June 30, 2026, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of June 30, 2026 and 2025, and the results of its operations and its cash flows for each of the years in the two-year period ended June 30, 2026, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s consolidated financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting, but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing separate opinions on the critical audit matter or on the accounts or disclosures to which it relates.

Allowance for Credit Losses on Loans

As described in Notes 1 and 4 to the consolidated financial statements, the Company accounts for an allowance for credit losses on loans (“ACL”) in accordance with Financial Accounting Standards Board Accounting Standard Codification (“ASC”) Topic 326, Financial Instruments-Credit Losses. ASC 326 requires the Company's loan portfolio, measured at amortized cost, to be presented at the net amount expected to be collected. Estimates of the ACL are based on evaluation of the size of the portfolio, current risk characteristics, past events, current economic conditions, reasonable and

supportable forecasts of future economic conditions, and loan prepayment and curtailment experience. The ACL as of June 30, 2026 was $1.7 million.

The Company’s methodology for estimating the ACL includes both quantitative and qualitative components. The Company’s loan portfolio is segmented by loan types that behave similarly during economic cycles using a collective basis (“pooled loans”) for similar loans and an individual basis for loans that do not share similar risk characteristics. The quantitative analysis includes using a weighted-average remaining maturity (“WARM”) model for determining the ACL for pooled loans. The model requires management to apply historical loan charge-off rates to the weighted-average remaining contractual life of loans within each distinct loan pool. Additional management assumptions include, but are not limited to, loan prepayment speeds and loan curtailment rates. Management then applies qualitative adjustments to the quantitative model output. Management will also determine the ACL for individually evaluated loans. This component requires management to exercise high subjectivity in determining the expected future cash flows, underlying collateral value, and determining the timing of loan repayments of individually analyzed loans. The ACL methodology is inherently complex and requires the use of significant management judgment.

We determined that auditing the ACL was a critical audit matter because of the extent of auditor judgment applied and significant audit effort to evaluate the significant subjective and complex judgments made by management throughout the application processes, including loan pool segmentation, the weighted-average remaining contractual life of loans within the WARM model, the quantitative model assumptions discussed above, and the qualitative adjustments made to the quantitative outputs using the qualitative framework.

The primary audit procedures performed to address this critical audit matter included the following:

• Evaluated management’s judgments and assumptions related to the selection of the WARM model including evaluating the conceptual design of the model and the mathematical accuracy of the WARM model;

• Evaluated the relevance and reliability of the data used in the WARM model;

• Evaluated management’s judgments and assumptions used in the formation of the ACL for pooled loans, including the relevance and reliability of internal and external data used in their formulation;

• Evaluated management’s judgments and assumptions used in the formation of the ACL for individually evaluated loans, including the relevance and reliability of internal and external data used in their formulation including collateral value for collateral-dependent loans;

• Evaluated the relevance and reliability of the internal and external data used in the development of qualitative adjustments and the effect of those adjustments; and

• Evaluated management’s selection and use of a third-party service organization and specialist in assisting with the calculation of the ACL.

We have served as the Company’s auditor since 2020.

/s/Bonadio & Co., LLP

Pittsford, New York

September 16, 2026