diff --git a/.chronus/changes/fix-tcgc-client-init-2024-8-5-13-31-51.md b/.chronus/changes/fix-tcgc-client-init-2024-8-5-13-31-51.md
new file mode 100644
index 0000000000..a2bbccd0e2
--- /dev/null
+++ b/.chronus/changes/fix-tcgc-client-init-2024-8-5-13-31-51.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+Fix to add client signature `subscriptionId` for ARM SDK
diff --git a/packages/typespec-client-generator-core/package.json b/packages/typespec-client-generator-core/package.json
index b713d0118f..7cd67605a3 100644
--- a/packages/typespec-client-generator-core/package.json
+++ b/packages/typespec-client-generator-core/package.json
@@ -68,6 +68,7 @@
   },
   "devDependencies": {
     "@azure-tools/typespec-azure-core": "workspace:~",
+    "@azure-tools/typespec-azure-resource-manager": "workspace:~",
     "@types/node": "~18.11.19",
     "@types/pluralize": "^0.0.33",
     "@typespec/compiler": "workspace:~",
diff --git a/packages/typespec-client-generator-core/src/package.ts b/packages/typespec-client-generator-core/src/package.ts
index e6038d0c82..978b0f27f0 100644
--- a/packages/typespec-client-generator-core/src/package.ts
+++ b/packages/typespec-client-generator-core/src/package.ts
@@ -660,7 +660,18 @@ function addDefaultClientParameters<
   if (apiVersionParam) {
     client.initialization.properties.push(apiVersionParam);
   }
-  const subId = client.initialization.properties.find((x) => isSubscriptionId(context, x));
+  let subId = context.__clientToParameters
+    .get(client.__raw.type)
+    ?.find((x) => isSubscriptionId(context, x));
+  if (!subId && context.arm) {
+    for (const operationGroup of listOperationGroups(context, client.__raw)) {
+      // if any sub operation groups have an subId param, the top level needs it as well
+      subId = context.__clientToParameters
+        .get(operationGroup.type)
+        ?.find((x) => isSubscriptionId(context, x));
+      if (apiVersionParam) break;
+    }
+  }
   if (subId) {
     client.initialization.properties.push(subId);
   }
diff --git a/packages/typespec-client-generator-core/test/package.test.ts b/packages/typespec-client-generator-core/test/package.test.ts
index 34c7ed6609..6a40339599 100644
--- a/packages/typespec-client-generator-core/test/package.test.ts
+++ b/packages/typespec-client-generator-core/test/package.test.ts
@@ -1,5 +1,7 @@
 import { AzureCoreTestLibrary } from "@azure-tools/typespec-azure-core/testing";
+import { AzureResourceManagerTestLibrary } from "@azure-tools/typespec-azure-resource-manager/testing";
 import { ApiKeyAuth, OAuth2Flow, Oauth2Auth } from "@typespec/http";
+import { OpenAPITestLibrary } from "@typespec/openapi/testing";
 import { deepStrictEqual, ok, strictEqual } from "assert";
 import { beforeEach, describe, it } from "vitest";
 import {
@@ -2176,6 +2178,43 @@ describe("typespec-client-generator-core: package", () => {
       strictEqual(apiVersionOpParam.correspondingMethodParams[0], apiVersionClientParam);
     });
 
+    it("client level signatures by default", async () => {
+      const runnerWithArm = await createSdkTestRunner({
+        librariesToAdd: [AzureResourceManagerTestLibrary, AzureCoreTestLibrary, OpenAPITestLibrary],
+        autoUsings: ["Azure.ResourceManager", "Azure.Core"],
+        emitterName: "@azure-tools/typespec-java",
+      });
+      await runnerWithArm.compileWithBuiltInAzureResourceManagerService(`
+        model MyProperties {
+          @visibility("read")
+          @doc("Display name of the Azure Extended Zone.")
+          displayName: string;
+        }
+
+        @subscriptionResource
+        model MyModel is ProxyResource<MyProperties> {
+          @key("extendedZoneName")
+          @segment("extendedZones")
+          @path
+          name: string;
+        }
+
+        @armResourceOperations
+        interface MyInterface {
+          get is ArmResourceRead<MyModel>;
+        }
+      `);
+
+      const sdkPackage = runnerWithArm.context.sdkPackage;
+      const client = sdkPackage.clients[0].methods.find((x) => x.kind === "clientaccessor")
+        ?.response as SdkClientType<SdkHttpOperation>;
+      for (const name of ["apiVersion", "subscriptionId", "endpoint", "credential"]) {
+        const item = client.initialization.properties.find((x) => x.name === name);
+        ok(item !== undefined);
+        ok(item.onClient);
+      }
+    });
+
     it("default api version for operation is", async () => {
       await runner.compile(`
         namespace Azure.ResourceManager {
diff --git a/packages/typespec-client-generator-core/test/test-host.ts b/packages/typespec-client-generator-core/test/test-host.ts
index e8980de81b..87a72b016f 100644
--- a/packages/typespec-client-generator-core/test/test-host.ts
+++ b/packages/typespec-client-generator-core/test/test-host.ts
@@ -34,6 +34,7 @@ export interface SdkTestRunner extends BasicTestRunner {
   context: SdkContext<CreateSdkTestRunnerOptions, SdkHttpOperation>;
   compileWithBuiltInService(code: string): Promise<Record<string, Type>>;
   compileWithBuiltInAzureCoreService(code: string): Promise<Record<string, Type>>;
+  compileWithBuiltInAzureResourceManagerService(code: string): Promise<Record<string, Type>>;
   compileWithCustomization(mainCode: string, clientCode: string): Promise<Record<string, Type>>;
   compileWithVersionedService(code: string): Promise<Record<string, Type>>;
   compileAndDiagnoseWithCustomization(
@@ -165,6 +166,37 @@ export async function createSdkTestRunner(
       return result;
     };
 
+  // compile with dummy arm service definition
+  sdkTestRunner.compileWithBuiltInAzureResourceManagerService =
+    async function compileWithBuiltInAzureResourceManagerService(code) {
+      const result = await baseCompile(
+        `
+    @armProviderNamespace("My.Service")
+    @server("http://localhost:3000", "endpoint")
+    @service({title: "My.Service"})
+    @versioned(Versions)
+    @armCommonTypesVersion(CommonTypes.Versions.v5)
+    namespace My.Service;
+
+    /** Api versions */
+    enum Versions {
+      /** 2024-04-01-preview api version */
+      @useDependency(Azure.ResourceManager.Versions.v1_0_Preview_1)
+      V2024_04_01_PREVIEW: "2024-04-01-preview",
+    }
+    ${code}`,
+        {
+          noEmit: true,
+        }
+      );
+      sdkTestRunner.context = await createSdkContextTestHelper(
+        sdkTestRunner.program,
+        options,
+        sdkContextOption
+      );
+      return result;
+    };
+
   const mainAutoCode = [
     ...host.libraries
       .filter((x) => x !== StandardTestLibrary)
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 62402179ab..fde690ae41 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -2219,6 +2219,9 @@ importers:
       '@azure-tools/typespec-azure-core':
         specifier: workspace:~
         version: link:../typespec-azure-core
+      '@azure-tools/typespec-azure-resource-manager':
+        specifier: workspace:~
+        version: link:../typespec-azure-resource-manager
       '@types/node':
         specifier: ~18.11.19
         version: 18.11.19