diff --git a/uncloud_pay/models.py b/uncloud_pay/models.py
index 0c3dcf6..9de1631 100644
--- a/uncloud_pay/models.py
+++ b/uncloud_pay/models.py
@@ -399,8 +399,8 @@ class Bill(models.Model):
 
     @property
     def sum(self):
-        return 0
-#        for self.billrecord_set.
+        bill_records = BillRecord.objects.filter(bill=self)
+        return sum([ br.sum for br in bill_records ])
 
 
     @classmethod
@@ -525,9 +525,10 @@ class BillRecord(models.Model):
     starting_date = models.DateTimeField()
     ending_date = models.DateTimeField()
 
+    @property
     def quantity(self):
         """ Determine the quantity by the duration"""
-        if self.order.is_recurring:
+        if self.order.is_one_time:
             return 1
 
         record_delta = self.ending_date - self.starting_date
@@ -535,6 +536,7 @@ class BillRecord(models.Model):
         return record_delta.total_seconds()/self.order.recurring_period
 
 
+    @property
     def sum(self):
         return self.order.price * self.quantity
 
diff --git a/uncloud_pay/tests.py b/uncloud_pay/tests.py
index d2cdc34..6dc0aeb 100644
--- a/uncloud_pay/tests.py
+++ b/uncloud_pay/tests.py
@@ -27,14 +27,7 @@ class ProductActivationTestCase(TestCase):
             'description': 'One chocolate bar'
         }
 
-
-    def test_bill_one_time_order(self):
-        one_time_price = 10
-        recurring_price = 150
-        description = "Test Product 1"
-
-
-        order = Order.objects.create(
+        self.one_time_order = Order.objects.create(
                 owner=self.user,
                 starting_date=self.order_meta[1]['starting_date'],
                 ending_date=self.order_meta[1]['ending_date'],
@@ -44,15 +37,25 @@ class ProductActivationTestCase(TestCase):
                 billing_address=self.billing_address)
 
 
+    def test_bill_one_time_one_bill_record(self):
+        """
+        Ensure there is only 1 bill record per order
+        """
+
         bill = Bill.create_next_bill_for_user(self.user)
 
-        self.assertEqual(order.billrecord_set.count(), 1)
+        self.assertEqual(self.one_time_order.billrecord_set.count(), 1)
 
+    def test_bill_sum(self):
+        """
+        Ensure there is only 1 bill record per order
+        """
+
+        bill = Bill.create_next_bill_for_user(self.user)
         self.assertEqual(bill.sum, self.order_meta[1]['price'])
 
 
 
-
 # class NotABillingTC(TestCase):
 # #class BillingTestCase(TestCase):
 #     def setUp(self):