As per my experience, we are paying ESIC on overtime as well. This is because we have to consider two aspects:
1. Employees should work for 8 hours a day. If something happens during that time, ESIC will take care of it, as this is usual and is their responsibility.
2. On the other hand, regarding overtime, it is separate from normal working hours. If something happens in that context, who will be responsible? If you go to ESIC to produce an accident report, will they accept it as it is? No, they will inquire about everything - shift time, time, and place of the accident.
If gross > 15000, no ESIC. If gross > 15000 + OT amount Rs. 4000, no ESIC. If Gross Rs. 14500 + OT amount Rs. 4000 = Paying ESIC on Rs. 18000. Consider these factors: the risk of work, place of work (machinery, chemicals, heavy electrical instruments), hours of work.
According to us, the employee and the risk upon us matter.