diff --git a/backend/hubspot_trigger_orchestrator/hubspot_deal_differ.py b/backend/hubspot_trigger_orchestrator/hubspot_deal_differ.py
index 9d66c637..50f3af04 100644
--- a/backend/hubspot_trigger_orchestrator/hubspot_deal_differ.py
+++ b/backend/hubspot_trigger_orchestrator/hubspot_deal_differ.py
@@ -9,6 +9,23 @@ class HubspotDealDiffer:
     def check_for_pashub_trigger(
         new_deal: Dict[str, str], old_deal: HubspotDealData
     ) -> bool:
+        """
+        Case 1: PasHub Link is updated
+        Case 2: Coordination is completed (and PasHub Link is populated)
+        Case 3: Design is completed (and PasHub Link is populated)
+        Case 4: Lodgement is completed (and PasHub Link is populated)
+        """
+        new_pashub_link: Optional[str] = new_deal["pashub_link"]
+        # Case 1
+        if not new_pashub_link:
+            return False
+
+        if not old_deal.pashub_link:
+            return True
+
+        if old_deal.pashub_link != new_pashub_link:
+            return True
+
         raise NotImplementedError
 
     @staticmethod