diff --git a/java/com/google/domain/registry/model/billing/BillingEvent.java b/java/com/google/domain/registry/model/billing/BillingEvent.java
index 39162ac24..bf7334edf 100644
--- a/java/com/google/domain/registry/model/billing/BillingEvent.java
+++ b/java/com/google/domain/registry/model/billing/BillingEvent.java
@@ -70,7 +70,12 @@ public abstract class BillingEvent extends ImmutableObject
     ANCHOR_TENANT,
     AUTO_RENEW,
     LANDRUSH,
-    SUNRISE
+    SUNRISE,
+    /**
+     * This flag will be added to any {@link OneTime} events that are created via, e.g., an
+     * automated process to expand {@link Recurring} events.
+     */
+    SYNTHETIC
   }
 
   /** Entity id. */
diff --git a/javatests/com/google/domain/registry/model/schema.txt b/javatests/com/google/domain/registry/model/schema.txt
index 4f26ac519..6953ee8de 100644
--- a/javatests/com/google/domain/registry/model/schema.txt
+++ b/javatests/com/google/domain/registry/model/schema.txt
@@ -26,6 +26,7 @@ enum com.google.domain.registry.model.billing.BillingEvent$Flag {
   AUTO_RENEW;
   LANDRUSH;
   SUNRISE;
+  SYNTHETIC;
 }
 class com.google.domain.registry.model.billing.BillingEvent$Modification {
   @Id long id;