Dear Tribikram,
Ex-gratia is Latin (lit. 'by favour') and is most often used in a legal context. When something has been done ex gratia, it has been done voluntarily, out of kindness or grace. In law, an ex gratia payment is a payment made without the giver recognising any liability or legal obligation.
Most of the cases Ex-gratia is paid along with annual bonus, since the Payment of Bonus Act, puts a cap on 20% bonus to employees, the employer and employee agree to pay a higher amount than 20%, and coined a new term of ex-gratia, which is paid along with Bonus.
Rgds,
Suresh Ramalingam
Consultant - Compliance