Washington promissory notes should highlight the relevant payment information. Set loan terms with larger payments at the end.CURRENCY: All principal and interest payments shall be made in lawful money of the United States. 7. Here's the information you'll need to have handy to complete your secured promissory note, installment with balloon final payment. If interest is charged, the rate should be included with a repayment schedule. The Washington Promissory Note template is a legal document, without which Washington state law won't recognize relations between the two parties as legal.