<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  11.3.0.1 -->
<!--Based on XBRL 2.1-->
<!--Created on: 5/7/2026 1:48:23 AM-->
<!--Modified on: 5/7/2026 1:48:23 AM-->
<xsd:schema targetNamespace="http://www.ibc.com/20260331" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:us-gaap="http://fasb.org/us-gaap/2025" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:us-roles="http://fasb.org/us-roles/2025" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:net="http://www.xbrl.org/2009/role/net" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:attributeFormDefault="unqualified" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2024-01-31" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:utr="http://www.xbrl.org/2009/utr" xmlns:srt="http://fasb.org/srt/2025" xmlns:deprecated="http://www.xbrl.org/2009/role/deprecated" xmlns:dei="http://xbrl.sec.gov/dei/2025" xmlns:iboc="http://www.ibc.com/20260331" xmlns:dtr="http://www.xbrl.org/2009/dtr" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" xmlns:ecd="http://xbrl.sec.gov/ecd/2025" xmlns:ecd-sub="http://xbrl.sec.gov/ecd-sub/2025">
  <xsd:annotation>
    <xsd:appinfo>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureStandardAndCustomAxisDomainDefaults" id="DisclosureStandardAndCustomAxisDomainDefaults">
        <link:definition>99900 - Disclosure - Standard And Custom Axis Domain Defaults</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfCondition" id="StatementConsolidatedStatementsOfCondition">
        <link:definition>995200100 - Statement - Consolidated Statements of Condition</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfIncome" id="StatementConsolidatedStatementsOfIncome">
        <link:definition>995200200 - Statement - Consolidated Statements of Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfComprehensiveIncome" id="StatementConsolidatedStatementsOfComprehensiveIncome">
        <link:definition>995200300 - Statement - Consolidated Statements of Comprehensive Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfCashFlows" id="StatementConsolidatedStatementsOfCashFlows">
        <link:definition>995200500 - Statement - Consolidated Statements of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesPortfolioCreditQualityDetails" id="DisclosureAllowanceForCreditLossesPortfolioCreditQualityDetails">
        <link:definition>99940407 - Disclosure - Allowance for Credit Losses - Portfolio Credit Quality (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsDetails" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsDetails">
        <link:definition>99940601 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsContractualMaturitiesAndEstimatedFairValuesDetails" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsContractualMaturitiesAndEstimatedFairValuesDetails">
        <link:definition>99940602 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Contractual Maturities and Estimated Fair Values (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsUnrealizedLossesDetails" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsUnrealizedLossesDetails">
        <link:definition>99940603 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Unrealized Losses (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsUnrealizedAndRealizedGainsAndLossesRecognizedInNetIncomeOnEquitySecuritiesDetails" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsUnrealizedAndRealizedGainsAndLossesRecognizedInNetIncomeOnEquitySecuritiesDetails">
        <link:definition>99940604 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Unrealized and realized gains and losses recognized in net income on equity securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfConditionParenthetical" id="StatementConsolidatedStatementsOfConditionParenthetical">
        <link:definition>995200105 - Statement - Consolidated Statements of Condition (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfComprehensiveIncomeParenthetical" id="StatementConsolidatedStatementsOfComprehensiveIncomeParenthetical">
        <link:definition>995200305 - Statement - Consolidated Statements of Comprehensive Income (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfShareholdersEquity" id="StatementConsolidatedStatementsOfShareholdersEquity">
        <link:definition>995200400 - Statement - Consolidated Statements of Shareholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/StatementConsolidatedStatementsOfShareholdersEquityParenthetical" id="StatementConsolidatedStatementsOfShareholdersEquityParenthetical">
        <link:definition>995200405 - Statement - Consolidated Statements of Shareholders' Equity (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureBasisOfPresentation" id="DisclosureBasisOfPresentation">
        <link:definition>995210101 - Disclosure - Basis of Presentation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureFairValueMeasurements" id="DisclosureFairValueMeasurements">
        <link:definition>995210201 - Disclosure - Fair Value Measurements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureLoans" id="DisclosureLoans">
        <link:definition>995210301 - Disclosure - Loans</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLosses" id="DisclosureAllowanceForCreditLosses">
        <link:definition>995210401 - Disclosure - Allowance for Credit Losses</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureStockOptions" id="DisclosureStockOptions">
        <link:definition>995210501 - Disclosure - Stock Options</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestments" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestments">
        <link:definition>995210601 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureOtherBorrowedFunds" id="DisclosureOtherBorrowedFunds">
        <link:definition>995210701 - Disclosure - Other Borrowed Funds</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureJuniorSubordinatedInterestDeferrableDebentures" id="DisclosureJuniorSubordinatedInterestDeferrableDebentures">
        <link:definition>995210801 - Disclosure - Junior Subordinated Interest Deferrable Debentures</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureCommonStockAndDividends" id="DisclosureCommonStockAndDividends">
        <link:definition>995210901 - Disclosure - Common Stock and Dividends</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureCommitmentsAndContingentLiabilities" id="DisclosureCommitmentsAndContingentLiabilities">
        <link:definition>995211001 - Disclosure - Commitments and Contingent Liabilities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureCapitalRatios" id="DisclosureCapitalRatios">
        <link:definition>995211101 - Disclosure - Capital Ratios</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureFairValueMeasurementsTables" id="DisclosureFairValueMeasurementsTables">
        <link:definition>99930203 - Disclosure - Fair Value Measurements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureLoansTables" id="DisclosureLoansTables">
        <link:definition>99930303 - Disclosure - Loans (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesTables" id="DisclosureAllowanceForCreditLossesTables">
        <link:definition>99930403 - Disclosure - Allowance for Credit Losses (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureStockOptionsTables" id="DisclosureStockOptionsTables">
        <link:definition>99930503 - Disclosure - Stock Options (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsTables" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsTables">
        <link:definition>99930603 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureJuniorSubordinatedInterestDeferrableDebenturesTables" id="DisclosureJuniorSubordinatedInterestDeferrableDebenturesTables">
        <link:definition>99930803 - Disclosure - Junior Subordinated Interest Deferrable Debentures (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureBasisOfPresentationDetails" id="DisclosureBasisOfPresentationDetails">
        <link:definition>99940101 - Disclosure - Basis of Presentation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureFairValueMeasurementsFairValueByLevelDetails" id="DisclosureFairValueMeasurementsFairValueByLevelDetails">
        <link:definition>99940201 - Disclosure - Fair Value Measurements - Fair Value By Level (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureFairValueMeasurementsFairValueMeasurementAndAssumptionsDetails" id="DisclosureFairValueMeasurementsFairValueMeasurementAndAssumptionsDetails">
        <link:definition>99940202 - Disclosure - Fair Value Measurements - Fair Value Measurement and Assumptions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureFairValueMeasurementsOtherAssumptionsDetails" id="DisclosureFairValueMeasurementsOtherAssumptionsDetails">
        <link:definition>99940203 - Disclosure - Fair Value Measurements - Other Assumptions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureLoansDetails" id="DisclosureLoansDetails">
        <link:definition>99940301 - Disclosure - Loans (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesCommercialRealEstateLoanPortfolioDetails" id="DisclosureAllowanceForCreditLossesCommercialRealEstateLoanPortfolioDetails">
        <link:definition>99940401 - Disclosure - Allowance for Credit Losses - Commercial real estate loan portfolio (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesByLoanClassDetails" id="DisclosureAllowanceForCreditLossesByLoanClassDetails">
        <link:definition>99940402 - Disclosure - Allowance for Credit Losses - By Loan Class (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesImpairmentByLoanClassDetails" id="DisclosureAllowanceForCreditLossesImpairmentByLoanClassDetails">
        <link:definition>99940403 - Disclosure - Allowance for Credit Losses - Impairment By Loan Class (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesNonAccrualBasisByLoanClassDetails" id="DisclosureAllowanceForCreditLossesNonAccrualBasisByLoanClassDetails">
        <link:definition>99940404 - Disclosure - Allowance for Credit Losses - Non-accrual Basis By Loan Class (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesImpairedLoansDetails" id="DisclosureAllowanceForCreditLossesImpairedLoansDetails">
        <link:definition>99940405 - Disclosure - Allowance for Credit Losses - Impaired Loans (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureAllowanceForCreditLossesAgingByLoanClassDetails" id="DisclosureAllowanceForCreditLossesAgingByLoanClassDetails">
        <link:definition>99940406 - Disclosure - Allowance for Credit Losses - Aging By Loan Class (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureStockOptionsOptionsDetails" id="DisclosureStockOptionsOptionsDetails">
        <link:definition>99940501 - Disclosure - Stock Options - Options (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureStockOptionsSarsDetails" id="DisclosureStockOptionsSarsDetails">
        <link:definition>99940502 - Disclosure - Stock Options - SARs (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsOtherInvestmentsDetails" id="DisclosureInvestmentSecuritiesEquitySecuritiesWithReadilyDeterminableFairValuesAndOtherInvestmentsOtherInvestmentsDetails">
        <link:definition>99940605 - Disclosure - Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Other Investments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureOtherBorrowedFundsDetails" id="DisclosureOtherBorrowedFundsDetails">
        <link:definition>99940701 - Disclosure - Other Borrowed Funds (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureJuniorSubordinatedInterestDeferrableDebenturesDetails" id="DisclosureJuniorSubordinatedInterestDeferrableDebenturesDetails">
        <link:definition>99940801 - Disclosure - Junior Subordinated Interest Deferrable Debentures (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureJuniorSubordinatedInterestDeferrableDebenturesKeyInformationDetails" id="DisclosureJuniorSubordinatedInterestDeferrableDebenturesKeyInformationDetails">
        <link:definition>99940802 - Disclosure - Junior Subordinated Interest Deferrable Debentures - Key Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureCommonStockAndDividendsDetails" id="DisclosureCommonStockAndDividendsDetails">
        <link:definition>99940901 - Disclosure - Common Stock and Dividends (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DisclosureCapitalRatiosDetails" id="DisclosureCapitalRatiosDetails">
        <link:definition>99941101 - Disclosure - Capital Ratios (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.ibc.com/role/DocumentDocumentAndEntityInformation" id="DocumentDocumentAndEntityInformation">
        <link:definition>995200090 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:type="simple" xlink:href="iboc-20260331_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="iboc-20260331_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="iboc-20260331_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="iboc-20260331_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:import namespace="https://xbrl.org/2023/calculation-1.1" schemaLocation="https://www.xbrl.org/2023/calculation-1.1.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/dei/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-2025.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/2024-01-31" schemaLocation="https://www.xbrl.org/dtr/type/2024-01-31/types.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/negated" schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" />
  <xsd:import namespace="http://fasb.org/us-roles/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/net" schemaLocation="http://www.xbrl.org/lrr/role/net-2009-12-16.xsd" />
  <xsd:import namespace="http://fasb.org/us-gaap/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd" />
  <xsd:import namespace="http://fasb.org/srt/2025" schemaLocation="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd-sub/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-sub-2025.xsd" />
  <xsd:element name="CommercialRealEstateFarmlandAndCommercialReceivableMember" id="iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CommercialRealEstateMultifamilyReceivableMember" id="iboc_CommercialRealEstateMultifamilyReceivableMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SpecialPassMember" id="iboc_SpecialPassMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="IncentiveStockOptionsTo10PercentShareholdersMember" id="iboc_IncentiveStockOptionsTo10PercentShareholdersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AccretionOfDiscountsInvestments" id="iboc_AccretionOfDiscountsInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="AmortizationOfInvestmentSecuritiesPremiums" id="iboc_AmortizationOfInvestmentSecuritiesPremiums" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="DistributionsFromOtherInvestments" id="iboc_DistributionsFromOtherInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="IncreaseDecreaseInNoninterestBearingDemandDeposits" id="iboc_IncreaseDecreaseInNoninterestBearingDemandDeposits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="IncreaseDecreaseInSavingAndInterestBearingDemandDeposits" id="iboc_IncreaseDecreaseInSavingAndInterestBearingDemandDeposits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="OtherBorrowedFundsDisclosureAbstract" id="iboc_OtherBorrowedFundsDisclosureAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ScheduleOfJuniorSubordinatedBorrowingsTableTextBlock" id="iboc_ScheduleOfJuniorSubordinatedBorrowingsTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NumberOfActiveOperatingSubsidiaries" id="iboc_NumberOfActiveOperatingSubsidiaries" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ImpairedFinancingReceivableRecordedInvestmentFairValueDisclosure" id="iboc_ImpairedFinancingReceivableRecordedInvestmentFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="ImpairedCommercialCollateralFinancingReceivableAppraisalsToDetermineFairValue" id="iboc_ImpairedCommercialCollateralFinancingReceivableAppraisalsToDetermineFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="OtherRealEstateAndForeclosedAssetsInUse" id="iboc_OtherRealEstateAndForeclosedAssetsInUse" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="ChangeInProvisionOfImpairedFinancingReceivableFairValueDisclosure" id="iboc_ChangeInProvisionOfImpairedFinancingReceivableFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="ChangeInProvisionOfOtherRealEstateAndForeclosedAssetsInUse" id="iboc_ChangeInProvisionOfOtherRealEstateAndForeclosedAssetsInUse" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="AllowanceForLoanLeaseLossesWriteOffsPriorToForeclosure" id="iboc_AllowanceForLoanLeaseLossesWriteOffsPriorToForeclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="FederalHomeLoanBankAdvancesLongTermFairValueDisclosure" id="iboc_FederalHomeLoanBankAdvancesLongTermFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsReductionsFromOutstandingAbstract" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsReductionsFromOutstandingAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsReductionsFromOutstandingWeightedAverageExercisePriceAbstract" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsReductionsFromOutstandingWeightedAverageExercisePriceAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueDisclosuresAbstract" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueDisclosuresAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NumberOfStatutoryBusinessTrustsIssuingPreferredSecurities" id="iboc_NumberOfStatutoryBusinessTrustsIssuingPreferredSecurities" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="MaximumNumberOfConsecutiveQuarterlyPeriodsAvailableForDeferralOfPaymentOfInterest" id="iboc_MaximumNumberOfConsecutiveQuarterlyPeriodsAvailableForDeferralOfPaymentOfInterest" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="MaximumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital" id="iboc_MaximumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="MinimumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierTwoCapital" id="iboc_MinimumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierTwoCapital" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital" id="iboc_CapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringNetOfReclassificationAdjustment" id="iboc_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringNetOfReclassificationAdjustment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="AllowanceForLoanAndLeaseLossesPeriodIncreaseDecreaseLoansTransferredToOtherRealEstateOwned" id="iboc_AllowanceForLoanAndLeaseLossesPeriodIncreaseDecreaseLoansTransferredToOtherRealEstateOwned" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="TrustTenMember" id="iboc_TrustTenMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="TrustTwelveMember" id="iboc_TrustTwelveMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="TrustElevenMember" id="iboc_TrustElevenMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="TrustNineMember" id="iboc_TrustNineMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ImpairedCollateralDependentCommercialLoansWithInternalEvaluationCompletedWithinLastTwelveMonths" id="iboc_ImpairedCollateralDependentCommercialLoansWithInternalEvaluationCompletedWithinLastTwelveMonths" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="ServiceChargesOnDepositAccountsMember" id="iboc_ServiceChargesOnDepositAccountsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OtherServiceChargesCommissionsAndFeesBankingMember" id="iboc_OtherServiceChargesCommissionsAndFeesBankingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OtherServiceChargesCommissionsAndFeesNonbankingMember" id="iboc_OtherServiceChargesCommissionsAndFeesNonbankingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CommercialFinancialAndAgriculturalRealEstatePortfolioSegmentMember" id="iboc_CommercialFinancialAndAgriculturalRealEstatePortfolioSegmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ForeignPortfolioSegmentMember" id="iboc_ForeignPortfolioSegmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element id="iboc_FinancingReceivableWatchListDoubtfulLoansRecordedInvestmentFairValueDisclosure" name="FinancingReceivableWatchListDoubtfulLoansRecordedInvestmentFairValueDisclosure" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element name="StockOptionPlan2012Member" id="iboc_StockOptionPlan2012Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="StockAppreciationRightsPlan2022Member" id="iboc_StockAppreciationRightsPlan2022Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShareBasedCompensationFairValueOfLiability" id="iboc_ShareBasedCompensationFairValueOfLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="DebtSecuritiesAvailableForSaleExcludingAccruedInterestMaturityAllocatedAndSingleMaturityDateAmortizedCostRollingMaturityAbstract" id="iboc_DebtSecuritiesAvailableForSaleExcludingAccruedInterestMaturityAllocatedAndSingleMaturityDateAmortizedCostRollingMaturityAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="DebtSecuritiesAvailableForSaleMaturityExcludingAccruedInterestAllocatedAndSingleMaturityDateRollingAfter5Through10YearsAmortizedCost" id="iboc_DebtSecuritiesAvailableForSaleMaturityExcludingAccruedInterestAllocatedAndSingleMaturityDateRollingAfter5Through10YearsAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="DebtSecuritiesAvailableForSaleMaturityExcludingAccruedInterestAllocatedAndSingleMaturityDateRollingAfter10YearsAmortizedCost" id="iboc_DebtSecuritiesAvailableForSaleMaturityExcludingAccruedInterestAllocatedAndSingleMaturityDateRollingAfter10YearsAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="DebtSecuritiesAvailableForSaleExcludingAccruedInterestMaturityWithoutSingleMaturityDateAmortizedCost" id="iboc_DebtSecuritiesAvailableForSaleExcludingAccruedInterestMaturityWithoutSingleMaturityDateAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableExcludingAccruedInterestYearSixOriginatedFiveYearsBeforeCurrentFiscalYearWriteoff" id="iboc_FinancingReceivableExcludingAccruedInterestYearSixOriginatedFiveYearsBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYearWriteoff" id="iboc_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="NumberOfLoansPlacedOnNonAccrual" id="iboc_NumberOfLoansPlacedOnNonAccrual" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsVestedAndExercisableNumber" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsVestedAndExercisableNumber" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExercisableWeightedAverageGrantDateFairValue" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExercisableWeightedAverageGrantDateFairValue" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExercisableWeightedAverageRemainingContractualTerms" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExercisableWeightedAverageRemainingContractualTerms" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVestedAndExercisable" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVestedAndExercisable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisedInPeriodWeightedAverageGrantDateFairValue" id="iboc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisedInPeriodWeightedAverageGrantDateFairValue" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="RetailMultiTenantMember" id="iboc_RetailMultiTenantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ResidentialAndCommercialMember" id="iboc_ResidentialAndCommercialMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="OneToFourFamilyConstructionMember" id="iboc_OneToFourFamilyConstructionMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="OwnerOccupiedRealEstateMember" id="iboc_OwnerOccupiedRealEstateMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CommercialLeasedPropertyMember" id="iboc_CommercialLeasedPropertyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FarmlandMember" id="iboc_FarmlandMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FinancingReceivableCommercialRealEstateLoanPortfolioDisaggregationByTypeTableTextBlock" id="iboc_FinancingReceivableCommercialRealEstateLoanPortfolioDisaggregationByTypeTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="Rule10b51ArrangementModifiedFlag" id="iboc_Rule10b51ArrangementModifiedFlag" type="xbrli:booleanItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="NonRule10b51ArrangementModifiedFlag" id="iboc_NonRule10b51ArrangementModifiedFlag" type="xbrli:booleanItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="RealEstateCollateralForFinancialReceivables" id="iboc_RealEstateCollateralForFinancialReceivables" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="RealEstateCollateralToTotalPercent" id="iboc_RealEstateCollateralToTotalPercent" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="O2025Q1DividendsMember" id="iboc_O2025Q1DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" id="iboc_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="IncreaseDecreaseInLongTermLoansFromOtherFederalHomeLoanBanks" id="iboc_IncreaseDecreaseInLongTermLoansFromOtherFederalHomeLoanBanks" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="NumberOfWhollyOwnedBankSubsidiaries" id="iboc_NumberOfWhollyOwnedBankSubsidiaries" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="NumberOfWhollyOwnedNonBankSubsidiaries" id="iboc_NumberOfWhollyOwnedNonBankSubsidiaries" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="O2026Q1DividendsMember" id="iboc_O2026Q1DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
</xsd:schema>