diff --git a/specification/app/resource-manager/Microsoft.App/preview/2023-05-02-preview/Subscriptions.json b/specification/app/resource-manager/Microsoft.App/preview/2023-05-02-preview/Subscriptions.json
new file mode 100644
index 000000000000..63a14405ea4f
--- /dev/null
+++ b/specification/app/resource-manager/Microsoft.App/preview/2023-05-02-preview/Subscriptions.json
@@ -0,0 +1,80 @@
+{
+  "swagger": "2.0",
+  "info": {
+    "version": "2023-05-02-preview",
+    "title": "ContainerApps API Client"
+  },
+  "host": "management.azure.com",
+  "schemes": [
+    "https"
+  ],
+  "consumes": [
+    "application/json"
+  ],
+  "produces": [
+    "application/json"
+  ],
+  "paths": {
+    "/subscriptions/{subscriptionId}/providers/Microsoft.App/getVerificationId": {
+      "post": {
+        "tags": [
+          "Subscriptions"
+        ],
+        "description": "Get the verification id of a subscription used for verifying custom domains",
+        "operationId": "GetVerificationId",
+        "parameters": [
+          {
+            "$ref": "../../../../../common-types/resource-management/v5/types.json#/parameters/SubscriptionIdParameter"
+          },
+          {
+            "$ref": "../../../../../common-types/resource-management/v5/types.json#/parameters/ApiVersionParameter"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK. The verification id has been returned successfully.",
+            "schema": {
+              "$ref": "#/definitions/VerificationId"
+            }
+          },
+          "default": {
+            "description": "Common error response.",
+            "schema": {
+              "$ref": "./CommonDefinitions.json#/definitions/DefaultErrorResponse"
+            }
+          }
+        },
+        "x-ms-examples": {
+          "List all operations": {
+            "$ref": "./examples/Subscriptions_GetVerificationId.json"
+          }
+        }
+      }
+    }
+  },
+  "definitions": {
+    "VerificationId": {
+      "description": "Verification Id of a subscription",
+      "type": "string",
+      "readOnly": true
+    }
+  },
+  "securityDefinitions": {
+    "azure_auth": {
+      "type": "oauth2",
+      "description": "Azure Active Directory OAuth2 Flow",
+      "flow": "implicit",
+      "authorizationUrl": "https://login.microsoftonline.com/common/oauth2/authorize",
+      "scopes": {
+        "user_impersonation": "impersonate your user account"
+      }
+    }
+  },
+  "security": [
+    {
+      "azure_auth": [
+        "user_impersonation"
+      ]
+    }
+  ]
+}
diff --git a/specification/app/resource-manager/Microsoft.App/preview/2023-05-02-preview/examples/Subscriptions_GetVerificationId.json b/specification/app/resource-manager/Microsoft.App/preview/2023-05-02-preview/examples/Subscriptions_GetVerificationId.json
new file mode 100644
index 000000000000..b7c00ff0d5a3
--- /dev/null
+++ b/specification/app/resource-manager/Microsoft.App/preview/2023-05-02-preview/examples/Subscriptions_GetVerificationId.json
@@ -0,0 +1,12 @@
+{
+  "parameters": {
+    "subscriptionId": "d27c3573-f76e-4b26-b871-0ccd2203d08c",
+    "api-version": "2023-05-02-preview"
+  },
+  "responses": {
+    "200": {
+      "headers": {},
+      "body": "5B406D5E790BBD224468CE0AA814C396203C7CE755F135A80E35D41865E51967"
+    }
+  }
+}
diff --git a/specification/app/resource-manager/readme.md b/specification/app/resource-manager/readme.md
index 9c52069b49e8..3f8eb8701a50 100644
--- a/specification/app/resource-manager/readme.md
+++ b/specification/app/resource-manager/readme.md
@@ -55,6 +55,7 @@ input-file:
   - Microsoft.App/preview/2023-05-02-preview/ManagedEnvironmentsDaprComponents.json
   - Microsoft.App/preview/2023-05-02-preview/ManagedEnvironmentsStorages.json
   - Microsoft.App/preview/2023-05-02-preview/SourceControls.json
+  - Microsoft.App/preview/2023-05-02-preview/Subscriptions.json
 directive:
   - suppress: OperationIdNounVerb
     from: Builds.json