Basis of Presentation	3 Months Ended
Mar. 31, 2021
Basis of Presentation
Basis of Presentation	Note 1 — Basis of Presentation Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America and to general practices within the banking industry. Our consolidated financial statements include the accounts of International Bancshares Corporation, and our wholly-owned bank subsidiaries, International Bank of Commerce, Laredo (“IBC”), Commerce Bank, International Bank of Commerce, Zapata, International Bank of Commerce, Brownsville, International Bank of Commerce, Oklahoma (the “Subsidiary Banks”) and our wholly-owned non-bank subsidiaries, IBC Trading Company, Premier Tierra Holdings, Inc., IBC Charitable and Community Development Corporation, Emerald Galveston Holdings, LLC and IBC Capital Corporation. Our consolidated financial statements are unaudited, but include all adjustments, which, in the opinion of management, are necessary for a fair presentation of the results of the periods presented. All such adjustments were of a normal and recurring nature. These financial statements should be read in conjunction with the financial statements and the notes thereto in our latest Annual Report on Form 10-K. Our consolidated statement of condition at December 31, 2020 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America (“US GAAP”) for complete financial statements. Certain reclassifications have been made to make prior periods comparable. Operating results for the three months ended March 31, 2021 are not necessarily indicative of the results for the year ending December 31, 2021 or any future period. We operate as one segment. The operating information used by our chief executive officer for purposes of assessing performance and making operating decisions is the consolidated statements presented in this report. We have five active operating subsidiaries, the Subsidiary Banks. We apply the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”), FASB ASC 280, “Segment Reporting,” in determining our reportable segments and related disclosures. We have evaluated all events or transactions that occurred through the date we issued these financial statements. During this period, we did not have any material recognizable or non-recognizable subsequent events. In June 2016, the FASB issued Accounting Standards Update No. 2016-13 to ASC 326, “Financial Instruments – Credit Losses.” The update amends existing standards for accounting for credit losses for financial assets. The update requires that the expected credit losses on the financial instruments held as of the end of the period being reported be measured based on historical experience, current conditions, and reasonable and supportable forecasts. The update also expands the required disclosures related to significant estimates and judgements used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s financial assets. The update also amended the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The impact of the adoption of the standard is to be recorded as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The accounting standard was effective for us on January 1, 2020. The task force formed last year, which includes key members of the teams that work with the current calculation of the allowance for probable loan losses plus members representing the corporate accounting and risk management areas, has worked with the implementation of the update and validation to complete our model/tool. Based on the composition of the portfolio at December 31, 2019 and after finalizing the methodology, the adoption of the update increased our allowance for probable loan losses (referred to as the allowance for credit losses under ASU 2016-13), by approximately 17.2%, resulting in a cumulative-effect adjustment to retained earnings of approximately $8.3 million, net of tax. Please refer to Note 4 – Allowance for Credit Losses and the Critical Accounting Policies discussion in Management’s Discussion and Analysis.

Basis of Presentation

3 Months Ended

Mar. 31, 2021

Note 1 — Basis of Presentation

Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America and to general practices within the banking industry. Our consolidated financial statements include the accounts of International Bancshares Corporation, and our wholly-owned bank subsidiaries, International Bank of Commerce, Laredo (“IBC”), Commerce Bank, International Bank of Commerce, Zapata, International Bank of Commerce, Brownsville, International Bank of Commerce, Oklahoma (the “Subsidiary Banks”) and our wholly-owned non-bank subsidiaries, IBC Trading Company, Premier Tierra Holdings, Inc., IBC Charitable and Community Development Corporation, Emerald Galveston Holdings, LLC and IBC Capital Corporation. Our consolidated financial statements are unaudited, but include all adjustments, which, in the opinion of management, are necessary for a fair presentation of the results of the periods presented. All such adjustments were of a normal and recurring nature. These financial statements should be read in conjunction with the financial statements and the notes thereto in our latest Annual Report on Form 10-K. Our consolidated statement of condition at December 31, 2020 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America (“US GAAP”) for complete financial statements. Certain reclassifications have been made to make prior periods comparable. Operating results for the three months ended March 31, 2021 are not necessarily indicative of the results for the year ending December 31, 2021 or any future period.

We operate as one segment. The operating information used by our chief executive officer for purposes of assessing performance and making operating decisions is the consolidated statements presented in this report. We have five active operating subsidiaries, the Subsidiary Banks. We apply the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”), FASB ASC 280, “Segment Reporting,” in determining our reportable segments and related disclosures.

We have evaluated all events or transactions that occurred through the date we issued these financial statements. During this period, we did not have any material recognizable or non-recognizable subsequent events.

In June 2016, the FASB issued Accounting Standards Update No. 2016-13 to ASC 326, “Financial Instruments – Credit Losses.” The update amends existing standards for accounting for credit losses for financial assets. The update requires that the expected credit losses on the financial instruments held as of the end of the period being reported be measured based on historical experience, current conditions, and reasonable and supportable forecasts. The update also expands the required disclosures related to significant estimates and judgements used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s financial assets. The update also amended the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The impact of the adoption of the standard is to be recorded as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The accounting standard was effective for us on January 1, 2020. The task force formed last year, which includes key members of the teams that work with the current calculation of the allowance for probable loan losses plus members representing the corporate accounting and risk management areas, has worked with the implementation of the update and validation to complete our model/tool. Based on the composition of the portfolio at December 31, 2019 and after finalizing the methodology, the adoption of the update increased our allowance for probable loan losses (referred to as the allowance for credit losses under ASU 2016-13), by approximately 17.2%, resulting in a cumulative-effect adjustment to retained earnings of approximately

$8.3 million, net of tax. Please refer to Note 4 – Allowance for Credit Losses and the Critical Accounting Policies discussion in Management’s Discussion and Analysis.