For part-time workers, the procedure of gratuity calculation remains the same. Since the amount of gratuity depends on the salary paid at the time of leaving the organization, and as a part-time employee is not expected to receive a salary on par with a full-time employee, no separate treatment is required.
The present salary (basic + DA) divided by 26 (to arrive at the daily wage), multiplied by 15 (to calculate 15 days' wages), and then multiplied by 20 (to determine gratuity for 20 years) will be the gratuity payable to the sweeper.
Regards, Madhu.T.K