diff --git a/docs/specification/embedded-checkout.md b/docs/specification/embedded-checkout.md
index 4ceb2ef5..ac27dd28 100644
--- a/docs/specification/embedded-checkout.md
+++ b/docs/specification/embedded-checkout.md
@@ -492,11 +492,11 @@ for `postMessage()` calls — before the `ec.ready` message is sent.
 Core messages are defined by the ECP specification and **MUST** be supported by
 all implementations. All messages are sent from Embedded Checkout to host.
 
-| Category         | Purpose                                                 | Pattern      | Core Messages                                                                        |
-| :--------------- | :------------------------------------------------------ | :----------- | :----------------------------------------------------------------------------------- |
-| **Handshake**    | Establish connection between host and Embedded Checkout | Request      | `ec.ready`                                                                           |
-| **Lifecycle**    | Inform of checkout state transitions                    | Notification | `ec.start`, `ec.complete`                                                            |
-| **State Change** | Inform of checkout field changes                        | Notification | `ec.line_items.change`, `ec.buyer.change`, `ec.payment.change`, `ec.messages.change` |
+| Category         | Purpose                                                 | Pattern      | Core Messages                                                                                            |
+| :--------------- | :------------------------------------------------------ | :----------- | :------------------------------------------------------------------------------------------------------- |
+| **Handshake**    | Establish connection between host and Embedded Checkout | Request      | `ec.ready`                                                                                               |
+| **Lifecycle**    | Inform of checkout state transitions                    | Notification | `ec.start`, `ec.complete`                                                                                |
+| **State Change** | Inform of checkout field changes                        | Notification | `ec.line_items.change`, `ec.buyer.change`, `ec.payment.change`, `ec.messages.change`, `ec.totals.change` |
 
 #### Extension Messages
 
@@ -825,6 +825,61 @@ informational notices about the checkout state.
 }
 ```
 
+#### `ec.totals.change`
+
+Checkout totals have been updated. This message covers all total line changes
+including taxes, fees, discounts, and fulfillment costs — many of which have no
+other domain-specific change message. Businesses **MUST** send this message
+whenever `checkout.totals` changes for any reason.
+
+When a change also triggers a domain-specific message (e.g.,
+`ec.line_items.change`, `ec.buyer.change`, or `ec.payment.change`), the business
+**MUST** send the domain-specific message first, then follow it with
+`ec.totals.change`.
+
+- **Direction:** Embedded Checkout → host
+- **Type:** Notification
+- **Payload:**
+    - `checkout`: The latest state of the checkout
+
+**Example Message:**
+
+```json
+{
+    "jsonrpc": "2.0",
+    "method": "ec.totals.change",
+    "params": {
+        "checkout": {
+            "id": "checkout_123",
+            // The entire checkout object is provided, including the updated totals
+            "totals": [
+                {
+                    "type": "subtotal",
+                    "display_text": "Subtotal",
+                    "amount": 4000
+                },
+                {
+                    "type": "fulfillment",
+                    "display_text": "Shipping",
+                    "amount": 599
+                },
+                {
+                    "type": "tax",
+                    "display_text": "Tax",
+                    "amount": 382
+                },
+                {
+                    "type": "total",
+                    "display_text": "Total",
+                    "amount": 4981
+                }
+            ]
+            // ...
+        }
+    }
+}
+```
+
 #### `ec.payment.change`
 
 Payment state has been updated. See [`ec.payment.change`](#ecpaymentchange) for
diff --git a/source/services/shopping/embedded.openrpc.json b/source/services/shopping/embedded.openrpc.json
index c7216e5c..f4830892 100644
--- a/source/services/shopping/embedded.openrpc.json
+++ b/source/services/shopping/embedded.openrpc.json
@@ -130,6 +130,22 @@
       ]
     },
 
+    {
+      "name": "ec.totals.change",
+      "summary": "Checkout totals changed",
+      "description": "Merchant notifies host that checkout.totals has changed. Covers all total line updates including taxes, fees, discounts, and fulfillment costs. For changes that also affect a specific domain (e.g., fulfillment cost update), this message MUST be sent after the domain-specific change message (e.g., ec.fulfillment.change).",
+      "params": [
+        {
+          "name": "checkout",
+          "required": true,
+          "schema": {
+            "$ref": "../../schemas/shopping/checkout.json",
+            "description": "Current checkout state with updated totals."
+          }
+        }
+      ]
+    },
+
     {
       "name": "ec.payment.change",
       "summary": "Payment state changed",