diff --git a/sale.py b/sale.py
index 9a6099715e..d209f7268f 100644
--- a/sale.py
+++ b/sale.py
@@ -7,12 +7,21 @@ from trytond.pool import PoolMeta
 class Sale(metaclass=PoolMeta):
     __name__ = 'sale.sale'
 
+    def must_check_credit_limit(self):
+        return self.shipment_method == 'order'
+
+    @property
+    def credit_limit_amount(self):
+        "Amount to check against credit limit"
+        return self.untaxed_amount
+
     @classmethod
     @ModelView.button
     @Workflow.transition('confirmed')
     def confirm(cls, sales):
         for sale in sales:
-            if sale.shipment_method == 'order':
+            if sale.must_check_credit_limit():
                 party = sale.invoice_party or sale.party
-                party.check_credit_limit(sale.untaxed_amount, origin=str(sale))
+                party.check_credit_limit(
+                    sale.credit_limit_amount, origin=str(sale))
         super(Sale, cls).confirm(sales)