Service tax applicable or not

Dear Sir,

Our company provied works contract services to government which is taxable w.e.f. 01.04.2015. In our case we had completed our work before 31st march 2015  and we have rasied invoice in the month of April 2015 and we got the payment of same in the month of July 2015. whether service tax applicable or not if applicable what will be the rate of service tax.