The word "ex-gratia" has not been defined in any labor enactment. As per the Oxford English Dictionary, ex gratia is a payment done from a sense of moral obligation rather than because of a legal requirement.
It is very clear, as per the pronouncement of various High Courts/Apex Court in their many judgments, that whether a particular item of payment is or is not a part of wages/salary must be decided independently of any contrary agreement between the parties. If the terms of appointment describe the payment of performance commission, it should be paid under the same head in the pay slip. The practice of an employer paying the same as ex gratia cannot be appreciated.
However, if any payment is made under the head ex gratia on a monthly basis, that would attract contributions towards PF/ESI. Any payment as ex gratia, at best, can be termed as an allowance and can be paid through the pay sheet for the purposes of CTC.
Regards,
Pkjain