Set loan terms with larger payments at the end. Here's the information you'll need to have handy to complete your secured promissory note, installment with balloon final payment.Maturity and Payment. All prepayments shall first be applied to outstanding late fees, then to accrued interest and thereafter to the principal loan amount. Here's the information you'll need to have handy to complete your unsecured promissory note, interest-only with balloon final payment. Borrower's estimated closing costs. 4.