diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 3ae2f928a44..2a5bae6b068 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -85,6 +85,7 @@ class SaleOrder(models.Model):
         default_team_id = self.env['crm.team']._get_default_team_id()
         return self.env['crm.team'].browse(default_team_id)
 
+    @api.constrains('fiscal_position_id')
     @api.onchange('fiscal_position_id')
     def _compute_tax_id(self):
         """
diff --git a/addons/website_sale/controllers/main.py b/addons/website_sale/controllers/main.py
index c5244b5a7d9..1e82a153509 100644
--- a/addons/website_sale/controllers/main.py
+++ b/addons/website_sale/controllers/main.py
@@ -625,7 +625,6 @@ class website_sale(http.Controller):
             partner_id = orm_partner.create(cr, SUPERUSER_ID, billing_info, context=context)
         order.write({'partner_id': partner_id, 'partner_invoice_id': partner_id})
         order_obj.onchange_partner_id(cr, SUPERUSER_ID, [order.id], context=context)
-        order_obj.onchange_partner_shipping_id(cr, SUPERUSER_ID, [order.id], context=context)
 
         # create a new shipping partner
         if checkout.get('shipping_id') == -1:
@@ -635,7 +634,8 @@ class website_sale(http.Controller):
             shipping_info['parent_id'] = partner_id
             checkout['shipping_id'] = orm_partner.create(cr, SUPERUSER_ID, shipping_info, context)
             order.write({'partner_shipping_id': checkout.get('shipping_id')})
-            order_obj.onchange_partner_shipping_id(cr, SUPERUSER_ID, [order.id], context=context)
+
+        order_obj.onchange_partner_shipping_id(cr, SUPERUSER_ID, [order.id], context=context)
 
         order_info = {
             'message_partner_ids': [(4, partner_id), (3, request.website.partner_id.id)],