One of my clients has wrongly deposited late fees in the coloumn of penalty and got refund of the same from the department in FY 19-20. He forgot to debit cash ledger balance by filing DRC-03. Till May 2022, the balance is not utilised for any other liability. In may 2022, he has filed DRC 03 and set off the refund. Whether interest will be applicable on unutilised cash balance (under penalty) from FY 19-20 to May 2022? Pls mention the provision and section applicable.