You will be able to use the Cashback amount even if your Wallet is Inactive.Cashback is given in the form of Gift Instrument.Gift Instrument is shown as a part of Freecharge Balance.
Will I stop receiving Cashbacks?
What does Inactive Freecharge Wallet mean?
How to Reactivate your Freecharge Wallet?
I have Freecharge Balance but I am not able to use it?