Dear Vasmin,
I would better request you kindly to go through the entire Code on Social Security,2020 so that you can clear your doubts on not only gratuity but also other social security measures like EPF, ESI etc., on your own.
Anyway, let me answer your query in a nut shell as follows:
Chapter V of the CSS,2020 covers the entire provisions of gratuity under sections 53 to 58.
No major changes except proportionate gratuity to fixed term workers on the actual length of service rendered.
The calculation of gratuity u/s 53 (2) shall be on the basis of the ' wages' as defined u/s 2(88) of the Code. The formula is similar to the present formula of the sum of basic and D.A subject to the proportionate addition of other allowances excluded in the case of short fall of the sum being less than 50% of the gross monthly wages.
Detailed explanation on continuous service has been given u/s 54 of the Code.