1. If night shift allowance is part of your regular business, it should be added to compute salary for the purpose of ESI
2. If your employer had been deducting ESI contribution from your salary for 20 months, then was there a reason for not asking upfront when they started doing it?
Now you can only ask your employer to refund the amount they have deducted from your salary but not force them. They money would have been deposited by them with the Department to provide you and your family an insurance and medical cover during this period, regardless of the fact whether you used it or not. You can always ask them to stop doing it in future.
27th February 2017 From India, New Delhi
if the regular duty is prescribed as night shift then, the employee can ask to merge the same as spl allowance,
but if the employee is working in daytime also, for some or other period, then night shift allowance is not paid,
if the daytime wages are below 21000/- gross then ESIC get applicable, and deducted even on night shift allowance also, however the employee can discuss the issue with employer to abolish the night shift allowance and alot it as special allowance, so that wages would get restructured, and he may get exit from ESIC, from april
28th February 2017