Hi Bharat,
An employee should complete 5years of sevice to be eligible for Gratuity. mentioning Gratuity in your CTC before the 5 year period of service is not a right thing. How ever some employers are considering it as a part of CTC which is not a fair practice.
In the fifth year you could include the component using the following calculation so as to cover the Cost to the company
Gratuity = Current basic X 15 X 5 / 26
wherein 5 is the number of years worked
Thanks & Regards,
Srilakshmi Korukonda