1. Reverse Charge Mechanism is applicable on supply of manpower service
2. Service Tax to be paid by your client will be
For the period of Jan to Mar 14, he was liable to pay @ 12.36% on 25% of 180000 = 5562/=
For the period of Apr to Sept 14, he was liable to pay @ 12.36% on 25% of 650000 = 20085/=
For the period of Jan to Mar 15, he was liable to pay @ 12.36% on 25% of 600000 = 18540/=
For the period of Apr to June 15, he was not liable to pay service tax as he is covered under full reverse charge.
Your client cannot avail SSP exemption as the service is covered under reverse charge mechanism. And hence liable to pay service tax for the period Jan 14 to Mar 15 as it is covered under partial reverse charge mechanism. However wef April 15 service is covered under full reverse charge mechanism and hence your client is not liable to pay service tax.
Since your client has not paid or charged any service tax until now, he will be liable for all the interest, penalty provisions also.
@ M V BHUVANA
Whatever you said regarding service provider registration is correct. But since the service is covered by RCM, hence registration is required from when the services are provided as it cannot avail SSP exemption.
Also that you mentioned about place of provision of service, it is for whether service tax is leviable or not. It is not whether RCM will apply or not.
And that regarding 2015-16 full RCM is correct.