Hi..........Ajay,
As per the provisions of Service Tax due date is 5th of next month (April to Feb.) and 31th for March.
Assuming due date is 05.10.10
up to 31.03.2011 = 177 days @ 13% = Rs.1576/-
from 01.04.2011 to 07.04.2011 = 7 days @ 18% = Rs.86/-
Total (1576+86)= Rs.1662/-