Hi,
The ESI contribution period will be:
1st April to 30th Sept
1st Oct to 31st March
If the wage of an employee exceeds the wage limit of Rs. 21,000 after April or October for the respective contribution periods, then the employee continues to be an employee till the end of that contribution period. Hence, the contribution is to be deducted and paid on the total wages earned. If the wages exceed Rs. 21,000/- in the middle of the contribution period, then the employee will continue to contribute to ESI till the end of the contribution period.