diff --git a/backend/benefit/calculator/api/v1/views.py b/backend/benefit/calculator/api/v1/views.py
index d8068705e9..179a1176bd 100644
--- a/backend/benefit/calculator/api/v1/views.py
+++ b/backend/benefit/calculator/api/v1/views.py
@@ -65,7 +65,7 @@ def patch(self, request, instalment_id):
                     application.save()
 
                 if instalment_status == InstalmentStatus.PAID:
-                    if instalment.instalment_number == 1:
+                    if instalment_count == 1:
                         application.talpa_status = (
                             ApplicationTalpaStatus.SUCCESSFULLY_SENT_TO_TALPA
                         )