diff --git a/.chronus/changes/fix-spread-access-2024-6-17-17-19-45.md b/.chronus/changes/fix-spread-access-2024-6-17-17-19-45.md
new file mode 100644
index 0000000000..d742b7b2f9
--- /dev/null
+++ b/.chronus/changes/fix-spread-access-2024-6-17-17-19-45.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+fix access and usage calculation for nested model/enum in spread model
\ No newline at end of file
diff --git a/packages/typespec-client-generator-core/src/types.ts b/packages/typespec-client-generator-core/src/types.ts
index deeb7ee94c..c75abe4aed 100644
--- a/packages/typespec-client-generator-core/src/types.ts
+++ b/packages/typespec-client-generator-core/src/types.ts
@@ -1330,9 +1330,8 @@ function updateTypesFromOperation(
         if (!context.spreadModels?.has(httpBody.type)) {
           context.spreadModels?.set(httpBody.type as Model, sdkType as SdkModelType);
         }
-      } else {
-        updateUsageOfModel(context, UsageFlags.Input, sdkType);
       }
+      updateUsageOfModel(context, UsageFlags.Input, sdkType);
       if (httpBody.contentTypes.some((x) => isJsonContentType(x))) {
         updateUsageOfModel(context, UsageFlags.Json, sdkType);
       }
@@ -1435,13 +1434,9 @@ function updateAccessOfModel(context: TCGCContext): void {
 
 function updateSpreadModelUsageAndAccess(context: TCGCContext): void {
   for (const sdkType of context.spreadModels?.values() ?? []) {
-    updateUsageOfModel(context, UsageFlags.Spread, sdkType);
-  }
-  for (const sdkType of context.modelsMap?.values() ?? []) {
-    // if a type only has spread usage, then it could be internal
-    if ((sdkType.usage & UsageFlags.Spread) > 0) {
-      sdkType.access = "internal";
-    }
+    // if a type has spread usage, then it must be internal
+    sdkType.access = "internal";
+    sdkType.usage = (sdkType.usage & ~UsageFlags.Input) | UsageFlags.Spread;
   }
 }
 
diff --git a/packages/typespec-client-generator-core/test/types/enum-types.test.ts b/packages/typespec-client-generator-core/test/types/enum-types.test.ts
index 67d73a446a..96c1c76c06 100644
--- a/packages/typespec-client-generator-core/test/types/enum-types.test.ts
+++ b/packages/typespec-client-generator-core/test/types/enum-types.test.ts
@@ -784,4 +784,31 @@ describe("typespec-client-generator-core: enum types", () => {
     strictEqual(enums[1].crossLanguageDefinitionId, "N.UD");
     strictEqual(enums[1].usage, UsageFlags.Input | UsageFlags.Json);
   });
+
+  it("spread and union as enum", async () => {
+    await runner.compile(
+      `
+        @service({})
+        namespace N {
+          union StringExtensibleNamedUnion {
+            string,
+            OptionB: "b",
+            "c",
+          }
+
+          model Test { name: string; }
+          op read(prop1: StringExtensibleNamedUnion; prop2: Test): void;
+        }
+      `
+    );
+    const enums = runner.context.sdkPackage.enums;
+    strictEqual(enums.length, 1);
+    strictEqual(enums[0].access, "public");
+    strictEqual(enums[0].usage, UsageFlags.Input | UsageFlags.Json);
+    const models = runner.context.sdkPackage.models;
+    const testModel = models.find((x) => x.name === "Test");
+    ok(testModel);
+    strictEqual(testModel.access, "public");
+    strictEqual(testModel.usage, UsageFlags.Input | UsageFlags.Json);
+  });
 });