INTERNATIONAL BANCSHARES CORP

Critical Accounting Policies

We have established various accounting policies which govern the application of accounting principles in the preparation of our consolidated financial statements. The significant accounting policies are described in the Notes to the Consolidated Financial Statements. Certain accounting policies involve significant subjective judgments and assumptions by management which have a material impact on the carrying value of certain assets and liabilities; management considers such accounting policies to be critical accounting policies.

We consider our estimated ACL as a policy critical to the sound operations of our Subsidiary Banks. The ACL is deducted from the amortized cost of an instrument to present the net amount expected to be collected on the financial asset. Our ACL primarily consists of the aggregate ACL estimates of our Subsidiary Banks. The estimates are established through charges to operations in the form of charges to provisions for credit loss expense. Loan losses or recoveries are charged or credited directly to the ACL. The ACL of each Subsidiary Bank is maintained at a level considered appropriate by management, based on estimated current expected credit losses in the current loan portfolio, including information about past events, current conditions, and reasonable and supportable forecasts.

The estimation of the ACL is based on a loss-rate methodology that measures lifetime losses on loan pools that have similar risk characteristics. Loans that do not have similar risk characteristics are evaluated on an individual basis. The segmentation of the loan portfolio into pools requires a balancing process between capturing similar risk characteristics and containing sufficient loss history to provide meaningful results. Our segmentation starts at the general loan category with further sub-segmentation based on collateral types that may be of meaningful size and/or may contain sufficient differences in risk characteristics based on management’s judgement that would warrant further segmentation. Risk management begins with a strong and conservative lending policy that specifies lending limits that are well below allowable regulatory limits, provides highly restrictive lending authority to lending officers, and promotes judicious lending terms and diversification. The general loan categories along with primary risk characteristics used in our calculation are as follows:

Commercial and industrial loans. This category includes loans extended to a diverse array of businesses for working capital or equipment purchases. These loans are mostly secured by the collateral pledged by the borrower that is directly related to the business activities of the borrower’s company such as equipment, accounts receivable and inventory. The borrower’s abilities to generate revenues from equipment purchases, collect accounts receivable, and to turn inventory into sales are risk factors in the repayment of the loan. A portion of this loan category is related to loans secured by oil and gas production and loans secured by aircraft.

Construction and land development loans. This category includes the development of land from unimproved land to lot development for both residential and commercial use and vertical construction across residential and commercial real estate classes. These loans carry risk of repayment when projects incur cost overruns, have an increase in the price of construction materials, encounter zoning, entitlement, and environmental issues, or encounter other factors that

may affect the completion of a project on time and on budget. Additionally, repayment risk may be negatively impacted when the market experiences a deterioration in the value of real estate. Risks specifically related to 1-4 family development loans also include mortgage rate risk and the practice by the mortgage industry of more restrictive underwriting standards, which inhibits the buyer from obtaining long term financing creating excessive housing and lot inventory in the market.

Commercial real estate loans. This category includes loans secured by farmland, multifamily properties, owner-occupied commercial properties, and non-owner-occupied commercial properties. Owner-occupied commercial properties include warehouses often along the U.S./Mexico border for import/export operations, office space where the borrower is the primary tenant, restaurants and other single-tenant retail spaces. Non-owner-occupied commercial properties include hotels, retail centers, office and professional buildings, and leased warehouses. These loans carry the risk of repayment when market values deteriorate, the business experiences turnover in key management, the business is unable to attract or maintain stable occupancy levels, or the market experiences an exit of a specific business type that is significant to the local economy, such as a manufacturing plant. Our primary risk management tool is internal monitoring measured against internal concentration limits that are significantly lower than regulatory thresholds and are segmented by low-risk and high-risk characteristics, such as the borrower’s equity, cash flow coverage, and non-amortizing versus amortizing status, further disaggregated by the length of time to pay in full. This monitoring is regularly reported to senior management and the board of directors. Risk management practices also extend to managing the borrower’s relationship with us and are designed to recognize degradation in the borrower’s ability to repay under established terms well before the borrower may default. Loan and deposit activity by the borrower is monitored on a frequent basis, which may prompt a change in risk classification. Once a loan is moved to a more severe risk classification, the loan performance, and when applicable, a plan by the borrower to rectify issues are monitored and reviewed at least quarterly. Additionally, our credit administration team, who is independent from the lending team, reviews a substantial portion of the commercial lending portfolio annually, which includes a significant portion of the commercial real estate loan portfolio given the current mix of loans in our portfolio. The table below summarizes the commercial real estate loan portfolio disaggregated by the type of real estate securing the credit as of December 31, 2025 and December 31, 2024:

*1-4 family mortgages.*This category includes both first and second lien mortgages for the purpose of home purchases or refinancing of existing mortgage loans. A small portion of this loan category is related to home equity lines of credits, lots purchases, and home construction. Loan repayments may be affected by unemployment or underemployment and deteriorating market values of real estate.

Consumer loans. This category includes deposit secured, vehicle secured, and unsecured loans, including overdrafts, made to individuals. Repayment is primarily affected by unemployment or underemployment.

The loan pools are further broken down using a risk-based segmentation based on internal classifications for commercial loans and past due status for consumer mortgage loans. Non-mortgage consumer loans are evaluated as one segment. On a weekly basis, commercial loan past due reports are reviewed by the credit quality committee to determine if a loan has any potential problems and if a loan should be placed on our internal Watch List report. Additionally, our credit department reviews the majority of our loans for proper internal classification purposes regardless of whether they are past due and segregates any loans with potential problems for further review. The credit department will discuss the potential problem loans with the servicing loan officers to determine any relevant issues that were not discovered in the evaluation. Also, an analysis of loans that is provided through examinations by regulatory authorities is considered in the review process. After the above analysis is completed, we will determine if a loan should be placed on an internal Watch List report because of issues related to the analysis of the credit, credit documents, collateral, and/or payment history.

Our internal Watch List report is segregated into the following categories: (i) Pass, (ii) Economic Monitoring, (iii) Special Review, (iv) Watch List—Pass, (v) Watch List—Substandard, and (vi) Watch List—Doubtful. Loans placed in the Economic Monitoring or Special Review categories reflect our opinion that the loans have potential weaknesses that require monitoring on a more frequent basis. Credits in those categories are reviewed and discussed on a regular basis with the credit department and the lending staff to determine if a change in category is warranted. Loans placed in the Watch List—Pass category reflect our opinion that the credit contains weaknesses that represent a greater degree of risk, which warrants “extra attention.” Credits placed in this category are reviewed and discussed on a regular basis with the credit department and the lending staff to determine if a change in category is warranted. Loans placed in the Watch List—Substandard category are considered to be potentially inadequately protected by the current sound worth and debt service capacity of the borrower or of any pledged collateral. Those credit obligations, even if apparently protected by collateral value, have shown defined weaknesses related to adverse financial, managerial, economic, market, or political conditions which may jeopardize repayment of principal under contractual terms. Furthermore, there is a possibility that we may sustain some future loss if such weaknesses are not corrected. Loans placed in the Watch List—Doubtful category have shown defined weaknesses and reflect our belief that it is likely, based on current information and events, that we will be unable to collect all principal and/or interest amounts contractually due. Loans placed in the Watch List—Doubtful category are placed on non-accrual when they are moved to that category.

For the purposes of the ACL, in order to maintain segments with sufficient history for meaningful results, the credits in the Pass and Economic Monitoring categories are aggregated, the credits in the Special Review and Watch List—Pass category are aggregated, and the credits in the Watch List—Substandard category remain in their own segment. For loans classified as Watch List—Doubtful, management evaluates these credits in accordance FASB ASC Subtopic 326-20, “Financial Instruments – Credit Losses – Measured at Amortized Cost,” and, if deemed necessary, a specific reserve is allocated to the loan. The analysis of the specific reserve is based on a variety of factors, including the borrower’s ability to pay, the economic conditions impacting the borrower’s industry and any collateral deficiency. If it is a collateral-dependent loan, the net realizable fair value of collateral will be evaluated for any deficiencies. Substantially all of our loans evaluated as Watch List – Doubtful are measured using the fair value of collateral method. In rare cases, we may use other methods to determine the specific reserve of a loan if such loan is not collateral dependent.

Within each collectively evaluated pool, the robustness of the lifetime historical loss-rate is evaluated and, if needed, is supplemented with peer loss rates through a model risk adjustment. Certain qualitative loss factors are then evaluated to incorporate management’s two-year reasonable and supportable forecast period followed by a reversion to the pool’s average lifetime loss-rate. Those qualitative loss factors are: (i) trends in portfolio volume and composition, (ii) volume and trends in classified loans, delinquencies and non-accruals, (iii) concentration risk, (iv) trends in underlying collateral value, (v) changes in policies, procedures, and strategies, and (vi) economic conditions. Qualitative factors also include potential losses stemming from operational risk factors arising from fraud, natural disasters, pandemics, geopolitical events and large loans. The large loan operational risk factor was added beginning in the second quarter of 2023. Because of the magnitude of large loans, they pose a higher risk of default. Recognizing this risk and establishing an operational risk factor to capture that risk, is prudent action in the current economic environment. Large loans are usually part of a larger relationship with collateral that is pledged across the relationship. Defaulting on a larger loan may

therefore jeopardize an entire collateral relationship. The current economic environment has created challenges for borrowers to service their debt. Increasing cap rates, elevated office vacancies, an upward trend in apartment vacancies and significant increases in interest rates are all contributing to the elevated risk in large loans. Should any of the factors considered by management in evaluating the adequacy of the ACL change, our estimate could also change, which could affect the level of future credit loss expense.

We have elected to not measure an ACL for accrued interest receivable given our timely approach in identifying and writing off uncollectible accrued interest. An ACL for off-balance sheet exposure is derived from a projected usage rate of any unfunded commitment multiplied by the historical loss rate, plus model risk adjustment, if any, of the on-balance sheet loan pools.

Our management continually reviews the ACL of the Subsidiary Banks using the amounts determined from the estimates established on specific doubtful loans, the estimate established on quantitative historical loss percentages, and the estimate based on qualitative current conditions and reasonable and supportable two-year forecasted data. Our methodology reverts to the average lifetime loss-rate beyond the forecast period when we can no longer develop reasonable and supportable forecasts. Should any of the factors considered by management in evaluating the adequacy of the estimate for current expected credit losses change, our estimate of current expected credit losses could also change, which could affect the level of future credit loss expense. While the calculation of our ACL utilizes management’s best judgment and all information reasonably available, the adequacy of the ACL is dependent on a variety of factors beyond our control, including, among other things, the performance of the entire loan portfolio, the economy, government actions, changes in interest rates and the view of regulatory authorities towards loan classifications.