Determine ESI applicability on actual wage falling below Rs. 21,000 due to short attendance and reduced incentives

A person is earning wages (Basic +DA +Monthly Allowances(Fixed & Variable) ) well above the limit of Rs.21,000, therefore he was Not covered under ESI. However, if in any month his calculated wages fall below Rs.21,000 due to unpaid leaves and reduction(deduction) of performance-based incentives, then are we liable to deduct ESIC for that month? And does that bring him under ESI henceforth?

@Narendra
ESIC applicability is on average gross wages, and if it goes reduced due to absence or salary deduction. it does not get implemented on the excluded employee, because if the full month salary would be calculated it would surely goes above 21000/- so they are not to be included
Performance incentive is not part of wages, please be updated