@api.multi
    def action_invoice_open(self):
        for inv in self:
            sequence_obj = self.env['ir.sequence'].sudo()
            if inv.type == "out_invoice" and inv.journal_id.ncf_control:
                if not inv.partner_id.sale_fiscal_type:
                    raise ValidationError(_(
                        u"El cliente [{}]{} no tiene Tipo de comprobante, y es requerido"
                        "para este tipo de factura.".format(inv.partner_id.id,
                                                            inv.partner_id.name)))

                if inv.sale_fiscal_type in ("fiscal", "gov", "special") and not inv.partner_id.vat:
                    raise UserError(_(
                        u"El cliente [{}]{} no tiene RNC/Cédula, y es requerido"
                        "para este tipo de factura.".format(inv.partner_id.id,
                                                            inv.partner_id.name)))

                if inv.sale_fiscal_type == 'final' and inv.partner_id.vat:
                    if len(inv.partner_id.vat) == 9:
                        raise UserError(_(
                            u"No debe emitir una Factura de Consumo,"
                            " a un cliente con RNC."))

                if inv.amount_untaxed_signed >= 50000 and not inv.partner_id.vat:
                    raise UserError(_(
                        u"Si el monto es mayor a RD$50,000 el cliente debe "
                        u"tener un RNC o Céd para emitir la factura"))

            elif inv.type in ("in_invoice", "in_refund"):
                if inv.journal_id.purchase_type in ('normal', 'informal') and not inv.partner_id.vat:
                    raise UserError(_(
                        u"¡Para este tipo de Compra el Proveedor"
                        u" debe de tener un RNC/Cédula establecido!"))
                self.purchase_ncf_validate()

            if inv.type == "out_invoice":
                inv.internal_sequence = sequence_obj.next_by_code(
                    'client.invoice.number')
            if inv.type == "in_invoice":
                inv.internal_sequence = sequence_obj.next_by_code(
                    'supplier.invoice.number')
            #if inv.type == "in_refund":
            #    inv.internal_sequence = sequence_obj.next_by_code(
            #        'debit.note.invoice.number')
            #if inv.type == "out_refund":
            #    inv.internal_sequence = sequence_obj.next_by_code(
            #        'credit.note.invoice.number')

        return super(AccountInvoice, self).action_invoice_open()