diff --git a/Web/app.py b/Web/app.py
index 49a0cdd..725c02d 100755
--- a/Web/app.py
+++ b/Web/app.py
@@ -3722,8 +3722,10 @@ def test_mahnungen():
                         or '—'
                 )
 
-                due_date_obj = record.get('DueDate')
-                days_overdue = (current_time - due_date_obj).days if due_date_obj else 0
+                due_date = appt.get('DueDate', current_time)
+                current_time_naive = current_time.replace(tzinfo=None)
+                due_date_naive = due_date.replace(tzinfo=None) if due_date else current_time_naive
+                days_overdue = (current_time_naive - due_date_naive).days
                 is_blocked = user_block_map.get(raw_user, False)
 
                 overdue_list.append({