Service tax under reverse charge

Dear All! Please clarify the following query. The company is providing service (construction of bridges, dams) to municipal bodies ie. government. Therefore, service tax on such output service is exempted. My query is the company (contractor) in turn receives the service from a sub contractor who in turn is exempted from service tax under the mega notification. The sub contractor is an individual and provides a works contract service. Is the company liable to pay it's portion of service tax under reverse charge?