Service tax doubt

Hi all,

I had this query in Service Tax. From July 2011, ST is to be charged on accrual basis so that means once the Bill is raised, ST Liability arises. My query is what if lets say in a future date, say August 10th, the invoice is cancelled. What is the correct accounting entry to be passed in this case. The ST amount for this bill has already been paid. How do we get such amount from the Department back?

Mohit