diff --git a/google/cloud/billing/v1/cloud_billing.proto b/google/cloud/billing/v1/cloud_billing.proto
index ae64248d637d1..0b0567545594d 100644
--- a/google/cloud/billing/v1/cloud_billing.proto
+++ b/google/cloud/billing/v1/cloud_billing.proto
@@ -247,13 +247,12 @@ message ProjectBillingInfo {
   // Output only. The resource name for the `ProjectBillingInfo`; has the form
   // `projects/{project_id}/billingInfo`. For example, the resource name for the
   // billing information for project `tokyo-rain-123` would be
-  // `projects/tokyo-rain-123/billingInfo`. This field is read-only.
+  // `projects/tokyo-rain-123/billingInfo`.
   string name = 1 [(google.api.field_behavior) = OUTPUT_ONLY];
 
   // Output only. The ID of the project that this `ProjectBillingInfo`
   // represents, such as `tokyo-rain-123`. This is a convenience field so that
-  // you don't need to parse the `name` field to obtain a project ID. This field
-  // is read-only.
+  // you don't need to parse the `name` field to obtain a project ID.
   string project_id = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
 
   // The resource name of the billing account associated with the project, if
@@ -263,7 +262,7 @@ message ProjectBillingInfo {
   // Output only. True if the project is associated with an open billing
   // account, to which usage on the project is charged. False if the project is
   // associated with a closed billing account, or no billing account at all, and
-  // therefore cannot use paid services. This field is read-only.
+  // therefore cannot use paid services.
   bool billing_enabled = 4 [(google.api.field_behavior) = OUTPUT_ONLY];
 }
 
@@ -391,7 +390,8 @@ message UpdateProjectBillingInfoRequest {
   // `projects/tokyo-rain-123`.
   string name = 1 [(google.api.field_behavior) = REQUIRED];
 
-  // The new billing information for the project. Read-only fields are ignored;
-  // thus, you can leave empty all fields except `billing_account_name`.
+  // The new billing information for the project. Output-only fields are
+  // ignored; thus, you can leave empty all fields except
+  // `billing_account_name`.
   ProjectBillingInfo project_billing_info = 2;
 }