Dear Rekha,
Gratuity will be calculated only on Basic Salary( Basic+ DA) and not on gross salary.
Gratuity - Last drawn Basic Salary(Basic+DA)/26 * 15 * Total no. of years.
Gratuity is normally calculated only for the person who had completed 5 yrs of service. There is a Judgement from Honorable Supreme court that a person who had completed 4 yrs and 8 months is eligible for Gratuity but this is applicable mostly where the employee has been terminated or lay-off, and also he has to work for 240 days in each year. Even the resigned employee can also apply but mostly it will be through legal proceedings.
If the employee had worked for less than six months the gratuity is calculated till the preceding year and if the employee works for more than 6 month then the gratuity has to be calculated for the full year.
For deceased employee, there is no 5 yrs or 4yrs and 240 days rule. If he has worked for more than 6 months his family has to be given 1 yr gratuity and so on.