Service tax on due basis or payment basis

Its correct, if invoice is dated 04.04.12, Service tax will be applicable @ 12.36%, even if service pertains to preceding year.

If the income is shown in the Second Half yearly return as march income, then you need pay only 10.3%.  In the point of taxation rules, there are some exemption available for individuals and firms for some specific services.  They can pay on receipt base instead of accrual.  See the latest notification in this regard.  For others if the invoice date is april 12, then service tax is leviable @ 12.36%.

rengaraj .r.k