What is Bonus Act? Is it mandatory?

The Payment of Bonus Act, 1965, gives to the employees a statutory right to a share in the profits of his employer. Prior to the enactment of the Act some employees used to get bonus but that was so if their employers were pleased to pay the same.
 
The Act enables the employees to get a minimum bonus equivalent to one month's salary or wages (8.33% of annual earnings) whether the employer makes any profit or not. But the Act also puts a ceiling on the bonus and the maximum bonus payable under the Act is equivalent to about 2 1/2 months' salary or wage (20% of annual earnings).