Here's the information you'll need to have handy to complete your unsecured promissory note, interest-only with balloon final payment. Here's the information you'll need to have handy to complete your secured promissory note, interest-only with balloon final payment.A single final balloon payment for the entire outstanding Principal amount and interest accrued will be paid on or before the day of. The add-on interest is added to the original principal amount, and becomes a part of the face amount of the promissory note. Adjustable-rate Mortgage (ARM)