Penal interest is an additional interest charge levied by a lender on a borrower who fails to make scheduled loan repayments — EMIs, interest installments, or principal repayments — on or before the specified due date. Penal interest serves as both a financial penalty for the borrower's failure to maintain repayment discipline and as compensation to the lender for the additional risk and administrative costs associated with delinquent accounts. In India, penal interest rates on home loans, personal loans, and business loans have historically ranged from 1% to 3% per annum above the contracted interest rate on the overdue amounts — effectively significantly increasing the real cost of delayed payments. Following RBI's November 2023 circular on penal charges in loan accounts, banks are no longer permitted to levy penal interest on overdue amounts — instead, a flat 'penal charge' (not compounded on existing interest) must be applied in a transparent, reasonable, and non-discriminatory manner. This regulatory change was driven by RBI's concern that complex and opaque penal interest structures were causing confusion among borrowers and leading to disproportionate charges. For investors evaluating NBFC and bank stocks, penal interest income — while a relatively small component of total interest income — can be an indicator of portfolio stress, as higher penal interest collections often signal rising borrower delinquency before NPAs are formally recognised in the provisioning cycle.