ARGOMENTO: Proposta a tutta la Community Italiana: Spesometro

 if user_company.vat_check_vies:
            # force full VIES online check
            check_func = self.vies_vat_check
        else:
            # quick and partial off-line checksum validation
            check_func = self.simple_vat_check

    def vies_vat_check(self, cr, uid, country_code, vat_number, context=None):
        try:
            # Validate against  VAT Information Exchange System (VIES)
            # see also http://ec.europa.eu/taxation_customs/vies/
            return vatnumber.check_vies(country_code.upper()+vat_number)
        except Exception:
            # see http://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl
            # Fault code may contain INVALID_INPUT, SERVICE_UNAVAILABLE, MS_UNAVAILABLE,
            # TIMEOUT or SERVER_BUSY. There is no way we can validate the input
            # with VIES if any of these arise, including the first one (it means invalid
            # country code or empty VAT number), so we fall back to the simple check.
            return self.simple_vat_check(cr, uid, country_code, vat_number, context=context)

    def check_vat(self, cr, uid, ids, context=None):
        user_company = self.pool.get('res.users').browse(cr, uid, uid).company_id
        if user_company.vat_check_vies:
            # force full VIES online check
            check_func = self.vies_vat_check
        else:
            # quick and partial off-line checksum validation
            check_func = self.simple_vat_check
        for partner in self.browse(cr, uid, ids, context=context):
            if not partner.vat:
                continue
            vat_country, vat_number = self._split_vat(partner.vat)
            if not check_func(cr, uid, vat_country, vat_number, context=context):
                return False
        return True

try:
    import vatnumber
except ImportError:
    logging.getLogger('base_vat').warning("VAT validation partially unavailable because the `vatnumber` Python library cannot be found. "
                                          "Install it to support more countries, for example with `easy_install vatnumber`.")

'external_dependencies': {
        'python': [
            'vatnumber',
        ]  
    }