diff --git a/.chronus/changes/copilot-add-subscription-id-parameter-again-2026-0-26-3-0-31.md b/.chronus/changes/copilot-add-subscription-id-parameter-again-2026-0-26-3-0-31.md
new file mode 100644
index 0000000000..9fcc9a7f25
--- /dev/null
+++ b/.chronus/changes/copilot-add-subscription-id-parameter-again-2026-0-26-3-0-31.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+Fix subscriptionId and apiVersion client parameters not propagating to top-level client when nested operation groups contain these parameters
\ No newline at end of file
diff --git a/packages/typespec-client-generator-core/src/clients.ts b/packages/typespec-client-generator-core/src/clients.ts
index 99fd2fbe72..5d92791c2d 100644
--- a/packages/typespec-client-generator-core/src/clients.ts
+++ b/packages/typespec-client-generator-core/src/clients.ts
@@ -253,7 +253,10 @@ function addDefaultClientParameters<
       // if any sub operation groups have an api version param, the top level needs
       // the api version param as well
       apiVersionParam = context.__clientParametersCache.get(sc)?.find((x) => x.isApiVersionParam);
-      if (apiVersionParam) break;
+      if (apiVersionParam) {
+        context.__clientParametersCache.get(client.__raw)?.push(apiVersionParam);
+        break;
+      }
     }
   }
   if (apiVersionParam) {
@@ -276,7 +279,10 @@ function addDefaultClientParameters<
     for (const sc of listOperationGroups(context, client.__raw)) {
       // if any sub operation groups have an subId param, the top level needs it as well
       subId = context.__clientParametersCache.get(sc)?.find((x) => isSubscriptionId(context, x));
-      if (subId) break;
+      if (subId) {
+        context.__clientParametersCache.get(client.__raw)?.push(subId);
+        break;
+      }
     }
   }
   if (subId) {
diff --git a/packages/typespec-client-generator-core/test/decorators/client-location.test.ts b/packages/typespec-client-generator-core/test/decorators/client-location.test.ts
index 89de40e533..05e63ae24f 100644
--- a/packages/typespec-client-generator-core/test/decorators/client-location.test.ts
+++ b/packages/typespec-client-generator-core/test/decorators/client-location.test.ts
@@ -919,4 +919,107 @@ describe("Parameter", () => {
     strictEqual(subIdParam.correspondingMethodParams.length, 1);
     strictEqual(subIdParam.correspondingMethodParams[0], subIdMethodParam);
   });
+
+  it("subscriptionId on client when clientLocation moves it to method level for some operations in nested operation groups", async () => {
+    const runnerWithArm = await createSdkTestRunner({
+      librariesToAdd: [AzureResourceManagerTestLibrary, AzureCoreTestLibrary, OpenAPITestLibrary],
+      autoUsings: ["Azure.ResourceManager", "Azure.Core"],
+      emitterName: "@azure-tools/typespec-java",
+    });
+    await runnerWithArm.compile(
+      `
+      @armProviderNamespace("Microsoft.Contoso")
+      @service(#{
+        title: "Microsoft.Contoso management service",
+      })
+      @versioned(Microsoft.Contoso.Versions)
+      namespace Microsoft.Contoso;
+
+      /** The available API versions. */
+      enum Versions {
+        /** 2021-10-01-preview version */
+        @armCommonTypesVersion(CommonTypes.Versions.v5)
+        v2021_10_01_preview: "2021-10-01-preview",
+      }
+
+      /** Employee resource */
+      model Employee is TrackedResource<EmployeeProperties> {
+        ...ResourceNameParameter<Employee>;
+      }
+
+      /** Employee properties */
+      model EmployeeProperties {
+        /** Age of employee */
+        age?: int32;
+      }
+
+      model EmployeeBaseParameter
+          is Azure.ResourceManager.Foundations.DefaultBaseParameters<Employee>;
+
+      namespace AnotherLayer {
+        @armResourceOperations
+        interface Employees {
+          createOrUpdate is ArmResourceCreateOrReplaceAsync<
+            Employee,
+            BaseParameters = EmployeeBaseParameter
+          >;
+          get is ArmResourceRead<Employee>;
+        }
+      }
+      @@clientLocation(EmployeeBaseParameter.subscriptionId, AnotherLayer.Employees.createOrUpdate);
+      `,
+    );
+
+    const sdkPackage = runnerWithArm.context.sdkPackage;
+    const client = sdkPackage.clients[0];
+    ok(client);
+
+    // The subscriptionId should exist at the client level because 'get' operation doesn't have clientLocation
+    // specified for subscriptionId, so it should remain on the client
+    const subIdClientParam = client.clientInitialization.parameters.find(
+      (p) => p.name === "subscriptionId",
+    );
+    ok(subIdClientParam);
+
+    // Check the AnotherLayer operation group
+    const anotherLayer = client.children?.find((c) => c.name === "AnotherLayer");
+    ok(anotherLayer);
+
+    // The operation group should also have subscriptionId in its parameters
+    const subIdNsParam = anotherLayer.clientInitialization.parameters.find(
+      (p) => p.name === "subscriptionId",
+    );
+    ok(subIdNsParam);
+
+    // Check the Employees operation group
+    const employees = anotherLayer.children?.find((c) => c.name === "Employees");
+    ok(employees);
+
+    // The operation group should also have subscriptionId in its parameters
+    const subIdOgParam = employees.clientInitialization.parameters.find(
+      (p) => p.name === "subscriptionId",
+    );
+    ok(subIdOgParam);
+
+    // The createOrUpdate method should have subscriptionId as a method parameter (not client)
+    const createOrUpdateMethod = employees.methods.find((m) => m.name === "createOrUpdate");
+    ok(createOrUpdateMethod);
+    const createOrUpdateSubIdParam = createOrUpdateMethod.parameters.find(
+      (p) => p.name === "subscriptionId",
+    );
+    ok(createOrUpdateSubIdParam);
+
+    // The get method should NOT have subscriptionId as a method parameter (it's on client)
+    const getMethod = employees.methods.find((m) => m.name === "get");
+    ok(getMethod);
+    const getSubIdMethodParam = getMethod.parameters.find((p) => p.name === "subscriptionId");
+    ok(!getSubIdMethodParam);
+
+    // But the get operation should reference the client subscriptionId parameter
+    const getOperation = getMethod.operation;
+    ok(getOperation);
+    const getSubIdOpParam = getOperation.parameters.find((p) => p.name === "subscriptionId");
+    ok(getSubIdOpParam);
+    strictEqual(getSubIdOpParam.methodParameterSegments[0][0], subIdOgParam);
+  });
 });