diff --git a/account.py b/account.py
index f4316494d2..aca6adc97a 100644
--- a/account.py
+++ b/account.py
@@ -40,6 +40,7 @@ class InvoiceLine:
     __metaclass__ = PoolMeta
     __name__ = 'account.invoice.line'
 
+    @fields.depends('origin')
     def _get_tax_rule_pattern(self):
         pool = Pool()
         SaleLine = pool.get('sale.line')
@@ -60,11 +61,3 @@ class InvoiceLine:
         pattern['from_country'] = from_country.id if from_country else None
         pattern['to_country'] = to_country.id if to_country else None
         return pattern
-
-    @fields.depends('origin')
-    def on_change_product(self):
-        super(InvoiceLine, self).on_change_product()
-
-    @fields.depends('origin')
-    def on_change_account(self):
-        super(InvoiceLine, self).on_change_account()
diff --git a/purchase.py b/purchase.py
index 4edfd3294c..23c1727a16 100644
--- a/purchase.py
+++ b/purchase.py
@@ -25,6 +25,8 @@ class PurchaseLine:
     __metaclass__ = PoolMeta
     __name__ = 'purchase.line'
 
+    @fields.depends('purchase', '_parent_purchase.warehouse',
+        '_parent_purchase.invoice_address')
     def _get_tax_rule_pattern(self):
         pattern = super(PurchaseLine, self)._get_tax_rule_pattern()
 
@@ -39,8 +41,3 @@ class PurchaseLine:
         pattern['from_country'] = from_country.id if from_country else None
         pattern['to_country'] = to_country.id if to_country else None
         return pattern
-
-    @fields.depends('_parent_purchase.warehouse',
-        '_parent_purchase.invoice_address')
-    def on_change_product(self):
-        super(PurchaseLine, self).on_change_product()
diff --git a/sale.py b/sale.py
index 85f91fc204..8081a6c024 100644
--- a/sale.py
+++ b/sale.py
@@ -25,6 +25,8 @@ class SaleLine:
     __metaclass__ = PoolMeta
     __name__ = 'sale.line'
 
+    @fields.depends('sale', '_parent_sale.warehouse',
+        '_parent_sale.shipment_address')
     def _get_tax_rule_pattern(self):
         pool = Pool()
         Location = pool.get('stock.location')
@@ -46,7 +48,3 @@ class SaleLine:
         pattern['from_country'] = from_country.id if from_country else None
         pattern['to_country'] = to_country.id if to_country else None
         return pattern
-
-    @fields.depends('_parent_sale.warehouse', '_parent_sale.shipment_address')
-    def on_change_product(self):
-        super(SaleLine, self).on_change_product()