diff --git a/src/services/estimation_service_v2.py b/src/services/estimation_service_v2.py
index b1af332..606b9b3 100644
--- a/src/services/estimation_service_v2.py
+++ b/src/services/estimation_service_v2.py
@@ -270,7 +270,7 @@ class EstimationService:
                 is_dtq = True
                 reason = "Declined due to high Rx spend"
 
-            if applicant_new_tier > applicant_tier:
+            if applicant_new_tier and applicant_new_tier > applicant_tier:
                 applicant_tier = applicant_new_tier
                 reason = f"Rx spend increased tier to {applicant_new_tier}."