diff --git a/addons/purchase/purchase.py b/addons/purchase/purchase.py
index 80e32bcfa42..7ffc65d93f9 100644
--- a/addons/purchase/purchase.py
+++ b/addons/purchase/purchase.py
@@ -301,7 +301,8 @@ class purchase_order(osv.osv):
                         raise osv.except_osv(_('Error !'), _('There is no expense account defined for this product: "%s" (id:%d)') % (ol.product_id.name, ol.product_id.id,))
                 else:
                     a = self.pool.get('ir.property').get(cr, uid, 'property_account_expense_categ', 'product.category')
-                a = self.pool.get('account.fiscal.position').map_account(cr, uid, o.partner_id, a)
+                fpos = o.fiscal_position or False
+                a = self.pool.get('account.fiscal.position').map_account(cr, uid, fpos, a)
                 il.append(self.inv_line_create(a,ol))
 
             a = o.partner_id.property_account_payable.id
@@ -445,7 +446,7 @@ class purchase_order_line(osv.osv):
         return super(purchase_order_line, self).copy(cr, uid, id, default, context)
 
     def product_id_change(self, cr, uid, ids, pricelist, product, qty, uom,
-            partner_id, date_order=False):
+            partner_id, date_order=False, fiscal_position=False):
         if not pricelist:
             raise osv.except_osv(_('No Pricelist !'), _('You have to select a pricelist in the purchase form !\nPlease set one before choosing a product.'))
         if not product:
@@ -488,7 +489,8 @@ class purchase_order_line(osv.osv):
 
         partner = self.pool.get('res.partner').browse(cr, uid, partner_id)
         taxes = self.pool.get('account.tax').browse(cr, uid,map(lambda x: x.id, prod.supplier_taxes_id))
-        res['value']['taxes_id'] = self.pool.get('account.fiscal.position').map_tax(cr, uid, partner, taxes)
+        fpos = fiscal_position and self.pool.get('account.fiscal.position').browse(cr, uid, fiscal_position) or False
+        res['value']['taxes_id'] = self.pool.get('account.fiscal.position').map_tax(cr, uid, fpos, taxes)
 
         res2 = self.pool.get('product.uom').read(cr, uid, [uom], ['category_id'])
         res3 = prod.uom_id.category_id.id
diff --git a/addons/purchase/purchase_view.xml b/addons/purchase/purchase_view.xml
index c0398b8bd5a..fb7e08a37f0 100644
--- a/addons/purchase/purchase_view.xml
+++ b/addons/purchase/purchase_view.xml
@@ -172,7 +172,7 @@
                 <form string="Purchase Order Line">
                     <notebook>
                         <page string="Order Line">
-                            <field colspan="4" context="partner_id=parent.partner_id,quantity=product_qty,pricelist=parent.pricelist_id,uom=product_uom,warehouse=parent.warehouse_id" name="product_id" on_change="product_id_change(parent.pricelist_id,product_id,product_qty,product_uom,parent.partner_id, parent.date_order)"/>
+                            <field colspan="4" context="partner_id=parent.partner_id,quantity=product_qty,pricelist=parent.pricelist_id,uom=product_uom,warehouse=parent.warehouse_id" name="product_id" on_change="product_id_change(parent.pricelist_id,product_id,product_qty,product_uom,parent.partner_id, parent.date_order, parent.fiscal_position)"/>
                             <field name="product_qty"/>
                             <field name="product_uom" on_change="product_uom_change(parent.pricelist_id,product_id,product_qty,product_uom,parent.partner_id, parent.date_order)"/>
                             <field colspan="4" name="name"/>
diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 165979976f4..58852e00d8b 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -785,7 +785,8 @@ class sale_order_line(osv.osv):
                 if uosqty:
                     pu = round(line.price_unit * line.product_uom_qty / uosqty,
                             int(config['price_accuracy']))
-                a = self.pool.get('account.fiscal.position').map_account(cr, uid, line.order_id.partner_id, a)
+                fpos = line.order_id.fiscal_position or False
+                a = self.pool.get('account.fiscal.position').map_account(cr, uid, fpos, a)
                 inv_id = self.pool.get('account.invoice.line').create(cr, uid, {
                     'name': line.name,
                     'origin':line.order_id.name,
@@ -849,7 +850,7 @@ class sale_order_line(osv.osv):
 
     def product_id_change(self, cr, uid, ids, pricelist, product, qty=0,
             uom=False, qty_uos=0, uos=False, name='', partner_id=False,
-            lang=False, update_tax=True, date_order=False, packaging=False):
+            lang=False, update_tax=True, date_order=False, packaging=False, fiscal_position=False):
         warning={}
         product_uom_obj = self.pool.get('product.uom')
         partner_obj = self.pool.get('res.partner')
@@ -905,11 +906,11 @@ class sale_order_line(osv.osv):
         result .update({'type': product_obj.procure_method})
         if product_obj.description_sale:
             result['notes'] = product_obj.description_sale
-
+        fpos = fiscal_position and self.pool.get('account.fiscal.position').browse(cr, uid, fiscal_position) or False
         if update_tax: #The quantity only have changed
             result['delay'] = (product_obj.sale_delay or 0.0)
             partner = partner_obj.browse(cr, uid, partner_id)
-            result['tax_id'] = self.pool.get('account.fiscal.position').map_tax(cr, uid, partner, product_obj.taxes_id)
+            result['tax_id'] = self.pool.get('account.fiscal.position').map_tax(cr, uid, fpos, product_obj.taxes_id)
 
         result['name'] = product_obj.partner_ref
         domain = {}
diff --git a/addons/sale/sale_view.xml b/addons/sale/sale_view.xml
index 5ef60c4e2ad..72511c2d1a5 100644
--- a/addons/sale/sale_view.xml
+++ b/addons/sale/sale_view.xml
@@ -118,19 +118,19 @@
                                             <field colspan="4"
                                                 context="partner_id=parent.partner_id,quantity=product_uom_qty,pricelist=parent.pricelist_id,shop=parent.shop_id,uom=product_uom"
                                                 name="product_id"
-                                                on_change="product_id_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], True, parent.date_order, product_packaging)"
+                                                on_change="product_id_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], True, parent.date_order, product_packaging, parent.fiscal_position)"
                                                 select="1"/>
                                             <field
                                                 context="partner_id=parent.partner_id,quantity=product_uom_qty,pricelist=parent.pricelist_id,shop=parent.shop_id,uom=product_uom"
                                                 name="product_uom_qty"
-                                                on_change="product_id_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], False, parent.date_order, product_packaging)"
+                                                on_change="product_id_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], False, parent.date_order, product_packaging, parent.fiscal_position)"
                                                 select="1"/>
                                             <field name="product_uom"
                                                 on_change="product_uom_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], False, parent.date_order)"/>
                                             <field
                                                 name="product_packaging"
                                                 context="partner_id=parent.partner_id,quantity=product_uom_qty,pricelist=parent.pricelist_id,shop=parent.shop_id,uom=product_uom"
-                                                on_change="product_id_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], False, parent.date_order, product_packaging)"
+                                                on_change="product_id_change(parent.pricelist_id,product_id,product_uom_qty,product_uom,product_uos_qty,product_uos,name,parent.partner_id, 'lang' in context and context['lang'], False, parent.date_order, product_packaging, parent.fiscal_position)"
                                                 domain="[('product_id','=',product_id)]"
                                                 groups="base.group_extended"/>
                                             <separator colspan="4" string="Manual Description"/>