Do I need to pay service tax on rental income

i am HINDU having 5 storage commercial building absolutely on my single name where groundfloor is given on rent by me & i m getting RS.6,50,000/- P.A, rest 2 floors i have given to my son on rent at rate of Rs.1,50,000/- P.A & another 2 floors at rent of Rs.1,50,000/- to my daughter in law with the rights of they can sublease on rent. my rental income is Rs. 9,50,000/- hence i m not collecting rent service tax from above three tenant nor i m paying service tax.the corporation tax & income tax on rent is paid by me. my son & daughter in law has sublated(as per their lease rights)& each of them are getting 5.5 lakhs + 5.5 lakhs rent, my QUST is Does this 3 rent of Rs 6,50,000/-+5,50,000/-+ 5,50,000/- will add back to my rental income & do i have to pay service tax or my rent will be considered Rs. 9,50,000/- which actual i m getting will be considered, & i dont have to pay service tax.in above situation if i dont have to pay service tax i required letter from advocate.i ll pay for it.