How to deal with service tax on this

Hi friends,

Assessees is a service provider, total cost of service provided by him was 50 Lakhs for F.Y.2011-12, and he just received 30 Lakh out it, till end of F.Y.2011-2012, but he has erroneously submitted his return for F.Y.2011-2012 to Service Tax Department without declaring remaining 20 lakh outstanding and service tax is payable on it, and he also submitted his Income Tax Return, and now he has received 10 lakh out of 20 lakhs .

The question is, is there any provision left for the assessees to rectify the above?

Is this possible for the assessees if he wants to pay the service tax on received amount now?

 Regards

Sandeep