A clause in a mortgage contract that says if the mortgage is prepaid within a certain time period, a penalty will be assessed. The penalty is usually based on percentage of the remaining mortgage balance or a certain number of months' worth of interest. Lenders write prepayment penalties into mortgage contracts to compensate for prepayment risk. As the incentive for a borrower to refinance a subprime mortgage is high, many subprime mortgages have prepayment penalties. VI prepay penalties are on a case by case scenario.