diff --git a/app/models.py b/app/models.py
index 5fff42027..50f3495d8 100644
--- a/app/models.py
+++ b/app/models.py
@@ -647,6 +647,7 @@ NOTIFICATION_STATUS_TYPES_BILLABLE = [
     NOTIFICATION_PERMANENT_FAILURE,
 ]
 
+
 NOTIFICATION_STATUS_TYPES = [
     NOTIFICATION_CREATED,
     NOTIFICATION_SENDING,
@@ -659,6 +660,8 @@ NOTIFICATION_STATUS_TYPES = [
     NOTIFICATION_PERMANENT_FAILURE,
 ]
 
+NOTIFICATION_STATUS_TYPES_NON_BILLABLE = list(set(NOTIFICATION_STATUS_TYPES) - set(NOTIFICATION_STATUS_TYPES_BILLABLE))
+
 NOTIFICATION_STATUS_TYPES_ENUM = db.Enum(*NOTIFICATION_STATUS_TYPES, name='notify_status_type')