Firm "X" is a manufacturer of vehicle input goods. At the same time , "X" receives materials from another company "Y" to process the same kind of goods for them with the help of the labour and equipments of Firm "X". The invoices that are raised against "Y" narrates as "Being invoice raised for labour charges". Will this be a taxable service ? And will service tax be applicable for this if the amount received over here exceeds the threshold limit?