diff --git a/addons/account/account.py b/addons/account/account.py
index 2b7c1a8e21d..0260c3fee5c 100644
--- a/addons/account/account.py
+++ b/addons/account/account.py
@@ -1561,14 +1561,15 @@ class account_tax_code(osv.osv):
                        (parent_ids,) + where_params)
         res=dict(cr.fetchall())
         obj_precision = self.pool.get('decimal.precision')
+        res2 = {} 
         for record in self.browse(cr, uid, ids, context=context):
             def _rec_get(record):
                 amount = res.get(record.id, 0.0)
                 for rec in record.child_ids:
                     amount += _rec_get(rec) * rec.sign
                 return amount
-            res[record.id] = round(_rec_get(record), obj_precision.precision_get(cr, uid, 'Account'))
-        return res
+            res2[record.id] = round(_rec_get(record), obj_precision.precision_get(cr, uid, 'Account'))
+        return res2
 
     def _sum_year(self, cr, uid, ids, name, args, context=None):
         if context is None: