Here's the information you'll need to have handy to complete your unsecured promissory note, interest-only with balloon final payment. A Promissory Note with Balloon Payments is a loan contract that enables a lender set loan terms with one or more larger payments at the end.Can be used for traditional installments or balloon payment. All payments shall first be applied to outstanding late fees, then to interest and the balance to the Principal amount. Here's the information you'll need to have handy to complete your secured promissory note, interest-only with balloon final payment. Deferral or balloon payment. 21.