Altough, the ceiling of ESIC deduction is capped at Rs.15000/Month Gross however earning as OT & incentives shall be added for determination of earned gross for the month,in case the fixed gross is upto Rs.15000/Month.
However,reimbursement of traveling expenses is not be clubbed on the fixed gross as the ESIC act itself exempts "Conveyance" from gross salary.
ESI is an applicable statutory compliance where the induvidual is applicable whose salary is lesser or equal to 15000 gross salary. In case if any allowances earned will not effect the ESI payable. Your ESI will effect at 1.75% and the employers by 4.75% irrespective to the wages/ allowances paid. Here the 4.75% is not contributed from the employees salary but employer remitts its share to the ESIC account.