diff --git a/uncloud_pay/models.py b/uncloud_pay/models.py
index 5f2b5d3..7232cd3 100644
--- a/uncloud_pay/models.py
+++ b/uncloud_pay/models.py
@@ -327,7 +327,7 @@ class Order(models.Model):
         One time orders have a recurring period of 0, so this work universally
         """
 
-        return self.starting_date + timedelta(seconds=self.recurring_period)
+        return self.starting_date + datetime.timedelta(seconds=self.recurring_period)
 
 
     @property
@@ -438,7 +438,7 @@ class Bill(models.Model):
                 starting_date = last_bill.starting_date
                 ending_date = bill.ending_date
             else:
-                starting_date = last_bill.end_date + datetime.timedelta(seconds=1)
+                starting_date = last_bill.ending_date + datetime.timedelta(seconds=1)
         else:
             if first_order:
                 starting_date = first_order.starting_date
@@ -566,6 +566,13 @@ class Bill(models.Model):
         # For each recurring order get the usage and bill it
 
 
+    def close(self):
+        """
+        Close/finish a bill
+        """
+
+        self.is_final = True
+        self.save()
 
 class BillRecord(models.Model):
     """
diff --git a/uncloud_pay/tests.py b/uncloud_pay/tests.py
index 9a26e2b..7acd7d4 100644
--- a/uncloud_pay/tests.py
+++ b/uncloud_pay/tests.py
@@ -188,9 +188,10 @@ class BillAndOrderTestCase(TestCase):
         """
 
         for ending_date in self.bill_dates:
-            Bill.create_next_bill_for_user(self.recurring_user, ending_date)
+            b = Bill.create_next_bill_for_user(self.recurring_user, ending_date)
+            b.close()
 
-        bills_count = Bill.objects.filter(owner=self.recurring_user).count()
+        bill_count = Bill.objects.filter(owner=self.recurring_user).count()
 
         self.assertEqual(len(self.bill_dates), bill_count)