@api.onchange('fiscal_category_id',
                  'fiscal_position',
                  'invoice_line_tax_id',
                  'quantity',
                  'price_unit',
                  'discount',
                  'insurance_value',
                  'freight_value',
                  'other_costs_value')
    def onchange_fiscal(self):
        ctx = dict(self.env.context)
        if self.invoice_id.type in ('out_invoice', 'out_refund'):
            ctx.update({'type_tax_use': 'sale'})
        else:
            ctx.update({'type_tax_use': 'purchase'})

        partner_id = self.invoice_id.partner_id.id or ctx.get('partner_id')
        company_id = self.invoice_id.company_id.id or ctx.get('company_id')
        if company_id and partner_id and self.fiscal_category_id:
            result = {'value': {}}
            kwargs = {
                'company_id': company_id,
                'partner_id': partner_id,
                'partner_invoice_id': self.invoice_id.partner_id.id,
                'product_id': self.product_id.id,
                'fiscal_category_id': self.fiscal_category_id.id,
                'context': ctx
            }
            result = self.with_context(ctx)._fiscal_position_map(
                result, **kwargs)

            kwargs.update({
                'invoice_line_tax_id': [
                    (6, 0, self.invoice_line_tax_id.ids)],
                'quantity': self.quantity,
                'price_unit': self.price_unit,
                'discount': self.discount,
                'fiscal_position': self.fiscal_position.id,
                'insurance_value': self.insurance_value,
                'freight_value': self.freight_value,
                'other_costs_value': self.other_costs_value,
            })
            result['value'].update(self._validate_taxes(kwargs))
            self.update(result['value'])

def on_change(record, method, args=None, kwargs=None):
    """Update `record` with the result of the on_change `method`"""
    res = record._odoo.execute_kw(record._name, method, args, kwargs)
    for k, v in res['value'].iteritems():
        setattr(record, k, v)

on_change(invoiceLine, 'onchange_fiscal', [],{})

onchange_fiscal() takes exactly 1 argument (3 given)