diff --git a/test/Microsoft.IdentityModel.JsonWebTokens.Tests/JsonWebTokenHandler.Extensibility.TokenType.cs b/test/Microsoft.IdentityModel.JsonWebTokens.Tests/JsonWebTokenHandler.Extensibility.TokenType.cs
new file mode 100644
index 0000000000..b791fe7bc2
--- /dev/null
+++ b/test/Microsoft.IdentityModel.JsonWebTokens.Tests/JsonWebTokenHandler.Extensibility.TokenType.cs
@@ -0,0 +1,263 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Diagnostics;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.IdentityModel.JsonWebTokens.Tests;
+using Microsoft.IdentityModel.Logging;
+using Microsoft.IdentityModel.TestUtils;
+using Microsoft.IdentityModel.Tokens;
+using Microsoft.IdentityModel.Tokens.Json.Tests;
+using Xunit;
+
+#nullable enable
+namespace Microsoft.IdentityModel.JsonWebTokens.Extensibility.Tests
+{
+    public partial class JsonWebTokenHandlerValidateTokenAsyncTests
+    {
+        [Theory, MemberData(nameof(TokenType_ExtensibilityTestCases), DisableDiscoveryEnumeration = true)]
+        public async Task ValidateTokenAsync_TokenTypeValidator_Extensibility(TokenTypeExtensibilityTheoryData theoryData)
+        {
+            var context = TestUtilities.WriteHeader($"{this}.{nameof(ValidateTokenAsync_TokenTypeValidator_Extensibility)}", theoryData);
+            context.IgnoreType = false;
+            for (int i = 0; i < theoryData.ExtraStackFrames; i++)
+                theoryData.TokenTypeValidationError!.AddStackFrame(new StackFrame(false));
+
+            try
+            {
+                ValidationResult<ValidatedToken> validationResult = await theoryData.JsonWebTokenHandler.ValidateTokenAsync(
+                    theoryData.JsonWebToken!,
+                    theoryData.ValidationParameters!,
+                    theoryData.CallContext,
+                    CancellationToken.None);
+
+                if (validationResult.IsValid)
+                {
+                    context.Diffs.Add("validationResult.IsValid is true, expected false");
+                }
+                else
+                {
+                    ValidationError validationError = validationResult.UnwrapError();
+                    IdentityComparer.AreValidationErrorsEqual(validationError, theoryData.TokenTypeValidationError, context);
+                    theoryData.ExpectedException.ProcessException(validationError.GetException(), context);
+                }
+            }
+            catch (Exception ex)
+            {
+                theoryData.ExpectedException.ProcessException(ex, context);
+            }
+
+            TestUtilities.AssertFailIfErrors(context);
+        }
+
+        public static TheoryData<TokenTypeExtensibilityTheoryData> TokenType_ExtensibilityTestCases
+        {
+            get
+            {
+                var theoryData = new TheoryData<TokenTypeExtensibilityTheoryData>();
+                CallContext callContext = new CallContext();
+
+                #region return CustomTokenTypeValidationError
+                // Test cases where delegate is overridden and return a CustomTokenTypeValidationError
+                // CustomTokenTypeValidationError : TokenTypeValidationError, ExceptionType: SecurityTokenInvalidTypeException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "CustomTokenTypeValidatorDelegate",
+                    CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorDelegate,
+                    extraStackFrames: 2)
+                {
+                    ExpectedException = new ExpectedException(
+                        typeof(SecurityTokenInvalidTypeException),
+                        nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorDelegate)),
+                    TokenTypeValidationError = new CustomTokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorDelegate), null),
+                        typeof(SecurityTokenInvalidTypeException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 160),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidationFailed)
+                });
+
+                // CustomTokenTypeValidationError : TokenTypeValidationError, ExceptionType: CustomSecurityTokenInvalidTypeException : SecurityTokenInvalidTypeException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "CustomTokenTypeValidatorCustomExceptionDelegate",
+                    CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorCustomExceptionDelegate,
+                    extraStackFrames: 2)
+                {
+                    ExpectedException = new ExpectedException(
+                        typeof(CustomSecurityTokenInvalidTypeException),
+                        nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorCustomExceptionDelegate)),
+                    TokenTypeValidationError = new CustomTokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorCustomExceptionDelegate), null),
+                        typeof(CustomSecurityTokenInvalidTypeException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 175),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidationFailed),
+                });
+
+                // CustomTokenTypeValidationError : TokenTypeValidationError, ExceptionType: NotSupportedException : SystemException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "CustomTokenTypeValidatorUnknownExceptionDelegate",
+                    CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorUnknownExceptionDelegate,
+                    extraStackFrames: 2)
+                {
+                    // CustomTokenTypeValidationError does not handle the exception type 'NotSupportedException'
+                    ExpectedException = ExpectedException.SecurityTokenException(
+                        LogHelper.FormatInvariant(
+                            Tokens.LogMessages.IDX10002, // "IDX10002: Unknown exception type returned. Type: '{0}'. Message: '{1}'.";
+                            typeof(NotSupportedException),
+                            nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorUnknownExceptionDelegate))),
+                    TokenTypeValidationError = new CustomTokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorUnknownExceptionDelegate), null),
+                        typeof(NotSupportedException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 205),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidationFailed),
+                });
+
+                // CustomTokenTypeValidationError : TokenTypeValidationError, ExceptionType: NotSupportedException : SystemException, ValidationFailureType: CustomAudienceValidationFailureType
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "CustomTokenTypeValidatorCustomExceptionCustomFailureTypeDelegate",
+                    CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorCustomExceptionCustomFailureTypeDelegate,
+                    extraStackFrames: 2)
+                {
+                    ExpectedException = new ExpectedException(
+                        typeof(CustomSecurityTokenInvalidTypeException),
+                        nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorCustomExceptionCustomFailureTypeDelegate)),
+                    TokenTypeValidationError = new CustomTokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.CustomTokenTypeValidatorCustomExceptionCustomFailureTypeDelegate), null),
+                        typeof(CustomSecurityTokenInvalidTypeException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 190),
+                        "JWT",
+                        CustomTokenTypeValidationError.CustomTokenTypeValidationFailureType),
+                });
+                #endregion
+
+                #region return TokenTypeValidationError
+                // Test cases where delegate is overridden and return an TokenTypeValidationError
+                // TokenTypeValidationError : ValidationError, ExceptionType:  SecurityTokenInvalidTypeException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "TokenTypeValidatorDelegate",
+                    CustomTokenTypeValidationDelegates.TokenTypeValidatorDelegate,
+                    extraStackFrames: 2)
+                {
+                    ExpectedException = new ExpectedException(
+                        typeof(SecurityTokenInvalidTypeException),
+                        nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorDelegate)),
+                    TokenTypeValidationError = new TokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorDelegate), null),
+                        typeof(SecurityTokenInvalidTypeException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 235),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidationFailed)
+                });
+
+                // TokenTypeValidationError : ValidationError, ExceptionType:  CustomSecurityTokenInvalidTypeException : SecurityTokenInvalidTypeException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "TokenTypeValidatorCustomTokenTypeExceptionTypeDelegate",
+                    CustomTokenTypeValidationDelegates.TokenTypeValidatorCustomTokenTypeExceptionTypeDelegate,
+                    extraStackFrames: 2)
+                {
+                    // TokenTypeValidationError does not handle the exception type 'CustomSecurityTokenInvalidTypeException'
+                    ExpectedException = ExpectedException.SecurityTokenException(
+                        LogHelper.FormatInvariant(
+                            Tokens.LogMessages.IDX10002, // "IDX10002: Unknown exception type returned. Type: '{0}'. Message: '{1}'.";
+                            typeof(CustomSecurityTokenInvalidTypeException),
+                            nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorCustomTokenTypeExceptionTypeDelegate))),
+                    TokenTypeValidationError = new TokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorCustomTokenTypeExceptionTypeDelegate), null),
+                        typeof(CustomSecurityTokenInvalidTypeException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 259),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidationFailed)
+                });
+
+                // TokenTypeValidationError : ValidationError, ExceptionType:  CustomSecurityTokenException : SystemException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "TokenTypeValidatorCustomExceptionTypeDelegate",
+                    CustomTokenTypeValidationDelegates.TokenTypeValidatorCustomExceptionTypeDelegate,
+                    extraStackFrames: 2)
+                {
+                    // TokenTypeValidationError does not handle the exception type 'CustomSecurityTokenException'
+                    ExpectedException = ExpectedException.SecurityTokenException(
+                        LogHelper.FormatInvariant(
+                            Tokens.LogMessages.IDX10002, // "IDX10002: Unknown exception type returned. Type: '{0}'. Message: '{1}'.";
+                            typeof(CustomSecurityTokenException),
+                            nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorCustomExceptionTypeDelegate))),
+                    TokenTypeValidationError = new TokenTypeValidationError(
+                        new MessageDetail(
+                            nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorCustomExceptionTypeDelegate), null),
+                        typeof(CustomSecurityTokenException),
+                        new StackFrame("CustomTokenTypeValidationDelegates.cs", 274),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidationFailed)
+                });
+
+                // TokenTypeValidationError : ValidationError, ExceptionType: SecurityTokenInvalidTypeException, inner: CustomSecurityTokenInvalidTypeException
+                theoryData.Add(new TokenTypeExtensibilityTheoryData(
+                    "TokenTypeValidatorThrows",
+                    CustomTokenTypeValidationDelegates.TokenTypeValidatorThrows,
+                    extraStackFrames: 1)
+                {
+                    ExpectedException = new ExpectedException(
+                        typeof(SecurityTokenInvalidTypeException),
+                        string.Format(Tokens.LogMessages.IDX10275),
+                        typeof(CustomSecurityTokenInvalidTypeException)),
+                    TokenTypeValidationError = new TokenTypeValidationError(
+                        new MessageDetail(
+                            string.Format(Tokens.LogMessages.IDX10275), null),
+                        typeof(SecurityTokenInvalidTypeException),
+                        new StackFrame("JsonWebTokenHandler.ValidateToken.Internal.cs", 250),
+                        "JWT",
+                        ValidationFailureType.TokenTypeValidatorThrew,
+                        new SecurityTokenInvalidTypeException(nameof(CustomTokenTypeValidationDelegates.TokenTypeValidatorThrows))
+                    )
+                });
+                #endregion
+
+                return theoryData;
+            }
+        }
+
+        public class TokenTypeExtensibilityTheoryData : ValidateTokenAsyncBaseTheoryData
+        {
+            internal TokenTypeExtensibilityTheoryData(string testId, TokenTypeValidationDelegate tokenTypeValidator, int extraStackFrames) : base(testId)
+            {
+                JsonWebToken = JsonUtilities.CreateUnsignedJsonWebToken("iss", "issuer");
+
+                ValidationParameters = new ValidationParameters
+                {
+                    AlgorithmValidator = SkipValidationDelegates.SkipAlgorithmValidation,
+                    AudienceValidator = SkipValidationDelegates.SkipAudienceValidation,
+                    IssuerValidatorAsync = SkipValidationDelegates.SkipIssuerValidation,
+                    IssuerSigningKeyValidator = SkipValidationDelegates.SkipIssuerSigningKeyValidation,
+                    LifetimeValidator = SkipValidationDelegates.SkipLifetimeValidation,
+                    SignatureValidator = SkipValidationDelegates.SkipSignatureValidation,
+                    TokenReplayValidator = SkipValidationDelegates.SkipTokenReplayValidation,
+                    TokenTypeValidator = tokenTypeValidator
+                };
+
+                ExtraStackFrames = extraStackFrames;
+            }
+
+            public JsonWebToken JsonWebToken { get; }
+
+            public JsonWebTokenHandler JsonWebTokenHandler { get; } = new JsonWebTokenHandler();
+
+            public bool IsValid { get; set; }
+
+            internal ValidatedTokenType ValidatedTokenType { get; set; }
+
+            internal TokenTypeValidationError? TokenTypeValidationError { get; set; }
+
+            internal int ExtraStackFrames { get; }
+        }
+    }
+}
+#nullable restore