Hi HardeepSR,
To my knowledge, there is no law making it compulsory to grant increment to employees. Generally increment is granted after every year of satisfactory performance/service or w.e.f. 1st April as per the policy of the employer. Also known as Annual increment. Outstanding performers are granted out-of-turn considerably. In some stray instances increment may not be granted as a routine every year. Even an average performer may be granted increment, it depends on various factors. Also increment is not a legal right enforceable.