diff --git a/specification/billing/resource-manager/Microsoft.Billing/stable/2021-10-01/billingSubscription.json b/specification/billing/resource-manager/Microsoft.Billing/stable/2021-10-01/billingSubscription.json
index 93bea1616b36..42740c53bc9c 100644
--- a/specification/billing/resource-manager/Microsoft.Billing/stable/2021-10-01/billingSubscription.json
+++ b/specification/billing/resource-manager/Microsoft.Billing/stable/2021-10-01/billingSubscription.json
@@ -736,6 +736,11 @@
           "type": "string",
           "readOnly": true
         },
+        "customerName": {
+          "description": "The name of the customer for whom the subscription was created. The field is applicable only for Microsoft Partner Agreement billing accounts.",
+          "type": "string",
+          "readOnly": true
+        },
         "displayName": {
           "description": "The name of the subscription.",
           "type": "string"