diff --git a/backend/app/plan/schemas.py b/backend/app/plan/schemas.py
index 5db3d4d1..96e967fb 100644
--- a/backend/app/plan/schemas.py
+++ b/backend/app/plan/schemas.py
@@ -1,5 +1,5 @@
 from pydantic import BaseModel, Field, BeforeValidator
-from typing import Annotated, List, Optional
+from typing import Annotated, List, Optional, Literal
 
 # Example constants for validation
 TYPICAL_MEASURE_TYPES = [
@@ -95,4 +95,4 @@ class PlanTriggerRequest(BaseModel):
 
     # When performing a remote assessment, if this has been set, it will allow the engine to
     # pull data from the find my epc website, to utilise as part of a remote assessment
-    event_type: Optional[float] = "remote_assessment",
+    event_type: Optional[Literal["remote_assessment"]] = None