Service tax calculation

Arpita kirankumar Shah (M.Com G.D.C.& A CA-IPC)   (43 Points)

07 January 2012  

service tax return has not been filed since oct 2008 and in books he has taken service tax @ 10 % flat on the value of services...

in order to calculate interest on delayed filing of return, is it 13% or 18 %??

also what about the service tax deducted on output services- client deducted @ 10 % for Apr '08 to feb'09 but it was 12% at that time.....???

what should be done?? whether the 2 % that has not been deducted should be deducted for Apr'08 to Feb'09 and then interest to be charged on the same??

kindly provide the answers