diff --git a/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/billing.json b/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/billing.json
index 9d2b4d8db7d7..1c1896e22cdc 100644
--- a/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/billing.json
+++ b/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/billing.json
@@ -106,6 +106,56 @@
             }
           }
         }
+      },
+      "patch": {
+        "tags": [
+          "BillingAccounts"
+        ],
+        "operationId": "BillingAccounts_Update",
+        "x-ms-long-running-operation": true,
+        "x-ms-long-running-operation-options": {
+          "final-state-via": "azure-async-operation"
+        },
+        "description": "The operation to update a billing account.",
+        "x-ms-examples": {
+          "UpdateBillingAccount": {
+            "$ref": "./examples/UpdateBillingAccount.json"
+          }
+        },
+        "parameters": [
+          {
+            "$ref": "#/parameters/apiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/billingAccountNameParameter"
+          },
+          {
+            "name": "parameters",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/BillingAccountUpdateProperties"
+            },
+            "description": "Parameters supplied to the update billing account operation."
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK. The request has succeeded.",
+            "schema": {
+              "$ref": "#/definitions/BillingAccount"
+            }
+          },
+          "202": {
+            "description": "Accepted. Billing account update is in progress."
+            },
+          "default": {
+            "description": "Error response describing why the operation failed.",
+            "schema": {
+              "$ref": "#/definitions/ErrorResponse"
+            }
+          }
+        }
       }
     },
     "/providers/Microsoft.Billing/billingAccounts/{billingAccountName}/billingProfiles/{billingProfileName}/availableBalance/default": {
@@ -3743,6 +3793,16 @@
         }
       }
     },
+    "BillingAccountUpdateProperties": {
+      "description": "The properties of the billing account that can be updated.",
+      "properties": {
+        "properties": {
+          "description": "A billing property.",
+          "x-ms-client-flatten": true,
+          "$ref": "#/definitions/BillingAccountProperties"
+        }
+      }
+    },
     "BillingProperty": {
       "description": "A billing property resource.",
       "type": "object",
diff --git a/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/examples/UpdateBillingAccount.json b/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/examples/UpdateBillingAccount.json
new file mode 100644
index 000000000000..693af0eb8693
--- /dev/null
+++ b/specification/billing/resource-manager/Microsoft.Billing/preview/2018-11-01-preview/examples/UpdateBillingAccount.json
@@ -0,0 +1,52 @@
+{
+  "parameters": {
+    "api-version": "2018-11-01-preview",
+    "billingAccountName": "{billingAccountName}",
+    "parameters": {
+      "properties": {
+        "address": {
+          "companyName": "Contoso",
+          "firstName": "Test",
+          "lastName": "User",
+          "addressLine1": "1 Microsoft Way",
+          "city": "Redmond",
+          "postalCode": "98052",
+          "region": "WA",
+          "country": "US"
+        }
+      }
+    }
+  },
+  "responses": {
+    "202": {
+      "headers": {
+        "Azure-AsyncOperation": "/providers/Microsoft.Billing/billingAccounts/{billingAccountName}/operationStatus/65e1f2bf-c31c-4b89-a599-25d9d4172af9?api-version=2018-11-01-preview",
+        "Retry-After": "10"
+      }
+    },
+    "200": {
+      "body": {
+        "id": "/providers/Microsoft.Billing/billingAccounts/{billingAccountName}",
+        "name": "{billingAccountName}",
+        "type": "Microsoft.Billing/billingAccounts",
+        "properties": {
+          "displayName": "Test Account",
+          "accountType": "Organization",
+          "address": {
+            "companyName": "Contoso",
+            "firstName": "Test",
+            "lastName": "User",
+            "addressLine1": "1 Microsoft Way",
+            "addressLine2": "",
+            "addressLine3": "",
+            "city": "Redmond",
+            "postalCode": "98052",
+            "region": "WA",
+            "country": "US"
+          },
+          "hasReadAccess": true
+        }
+      }
+    }
+  }
+}
\ No newline at end of file