A monthly interest rate can be included on the promissory note. Here's the information you'll need to have handy to complete your unsecured promissory note, interest-only with balloon final payment.Will the payments go toward both the interest and original loan amount? Interest-Only Payments (Balloon Payment). Acquire a North Carolina promissory note template to specify terms such as the principal amount, interest rate, and repayment duties. The North Carolina Unsecured Promissory Note Template is a legal form that establishes the various terms of a loan agreement. 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.