You can calculate the gratuity using this formula: Last Drawn BASIC + DA / 26 * 15 * number of years in continuous service. Anyone is entitled to gratuity after 5 years of service. If there is one day after six months, it should be counted as a full year. For example, if someone has completed 4 years and six months of service, they are entitled to gratuity. 15 days are mandatory as per the law, but it depends on the company's policy. The company can pay more than 15 days' salary in a year, such as 20 days, 30 days, or 90 days. Only Basic and DA will be treated as salary.