Thanks NIcola but i am not sure to understand 
In address_template.php I have this:
<?php
/**
* @package HikaShop for Joomla!
* @version 2.5.0
* @author hikashop.com
* @copyright (C) 2010-2015 HIKARI SOFTWARE. All rights reserved.
* @license GNU/GPLv3 http://www.gnu.org/licenses/gpl-3.0.html
*/
defined('_JEXEC') or die('Restricted access');
?>{address_company}
{address_title} {address_firstname} {address_lastname}
{address_street}
{address_post_code} {address_city} {address_state}
{address_country}
<?php echo JText::sprintf('TELEPHONE_IN_ADDRESS','{address_telephone}');?>
So I have to add address_vat to have that field value into the email??
Thanks
FRank