diff --git a/addons/account/account_invoice.py b/addons/account/account_invoice.py
index 32864f9477f..ece1b679776 100644
--- a/addons/account/account_invoice.py
+++ b/addons/account/account_invoice.py
@@ -1092,7 +1092,7 @@ class account_invoice(osv.osv):
         return map(lambda x: (0,0,x), lines)
 
     def refund(self, cr, uid, ids, date=None, period_id=None, description=None, journal_id=None):
-        invoices = self.read(cr, uid, ids, ['name', 'type', 'number', 'reference', 'comment', 'date_due', 'partner_id', 'address_contact_id', 'address_invoice_id', 'partner_contact', 'partner_insite', 'partner_ref', 'payment_term', 'account_id', 'currency_id', 'invoice_line', 'tax_line', 'journal_id'])
+        invoices = self.read(cr, uid, ids, ['name', 'type', 'number', 'reference', 'comment', 'date_due', 'partner_id', 'address_contact_id', 'address_invoice_id', 'partner_contact', 'partner_insite', 'partner_ref', 'payment_term', 'account_id', 'currency_id', 'invoice_line', 'tax_line', 'journal_id', 'user_id', 'fiscal_position'])
         obj_invoice_line = self.pool.get('account.invoice.line')
         obj_invoice_tax = self.pool.get('account.invoice.tax')
         obj_journal = self.pool.get('account.journal')
@@ -1141,7 +1141,8 @@ class account_invoice(osv.osv):
                 })
             # take the id part of the tuple returned for many2one fields
             for field in ('address_contact_id', 'address_invoice_id', 'partner_id',
-                    'account_id', 'currency_id', 'payment_term', 'journal_id'):
+                    'account_id', 'currency_id', 'payment_term', 'journal_id',
+                    'user_id', 'fiscal_position'):
                 invoice[field] = invoice[field] and invoice[field][0]
             # create the new invoice
             new_ids.append(self.create(cr, uid, invoice))
@@ -1362,17 +1363,6 @@ class account_invoice_line(osv.osv):
             taxes = res.supplier_taxes_id and res.supplier_taxes_id or (a and self.pool.get('account.account').browse(cr, uid, a, context=context).tax_ids or False)
         tax_id = fpos_obj.map_tax(cr, uid, fpos, taxes)
 
-        if type in ('in_invoice','in_refund') and tax_id and price_unit:
-            tax_pool = self.pool.get('account.tax')
-            tax_browse = tax_pool.browse(cr, uid, tax_id)
-            if not isinstance(tax_browse, list):
-                tax_browse = [tax_browse]
-            taxes = tax_pool.compute_inv(cr, uid, tax_browse, price_unit, 1)
-            tax_amount = reduce(lambda total, tax_dict: total + tax_dict.get('amount', 0.0), taxes, 0.0)
-            price_unit = price_unit - tax_amount
-            if qty != 0:
-                price_unit = price_unit / float(qty)
-
         if type in ('in_invoice', 'in_refund'):
             result.update( {'price_unit': price_unit or res.standard_price,'invoice_line_tax_id': tax_id} )
         else:
@@ -1488,13 +1478,19 @@ class account_invoice_line(osv.osv):
     #
     # Set the tax field according to the account and the fiscal position
     #
-    def onchange_account_id(self, cr, uid, ids, fposition_id, account_id):
+    def onchange_account_id(self, cr, uid, ids, product_id, partner_id, inv_type, fposition_id, account_id):
         if not account_id:
             return {}
         taxes = self.pool.get('account.account').browse(cr, uid, account_id).tax_ids
         fpos = fposition_id and self.pool.get('account.fiscal.position').browse(cr, uid, fposition_id) or False
-        res = self.pool.get('account.fiscal.position').map_tax(cr, uid, fpos, taxes)
-        return {'value':{'invoice_line_tax_id': res}}
+        tax_ids = self.pool.get('account.fiscal.position').map_tax(cr, uid, fpos, taxes)
+
+        product_change_result = self.product_id_change(cr, uid, ids, product_id, False, type=inv_type,
+                                                       partner_id=partner_id, fposition_id=fposition_id)
+        unique_tax_ids = set(tax_ids)
+        if product_change_result and 'value' in product_change_result and 'invoice_line_tax_id' in product_change_result['value']:
+            unique_tax_ids |= set(product_change_result['value']['invoice_line_tax_id'])
+        return {'value':{'invoice_line_tax_id': list(unique_tax_ids)}}
 
 account_invoice_line()