service tax on reted commercial property

there is a query regarding the service tax liabilities on rented commercial property rented from 1-04-07 and rent around 2500000/-,but till date no service tax collected and deposited the same, due to none aware of new amendment. Now we want to registered for it from 01-04-2009,so there is a query regarding the previous tax liabilities, interest & penalty.( these are payable or not).

Pls anyone suggest me on this query.

Regards

Rahul