A note rate is the interest rate that you pay on your mortgage loan, as stated on the promissory note that you sign when you agree to the terms of the loan. For example, if you take out a mortgage loan of $150,000 for 30 years at a 4 percent interest rate, your signature on the promissory note would express your agreement to pay the note rate of 4 percent. If your loan is a fixed-rate loan, the note rate would remain the same throughout the 30-year term of the loan. However, if your loan is an adjustable rate mortgage loan, the 4 percent note rate would be the initial interest rate that you would pay on the loan until the rate adjusts to a higher or lower interest rate after the initial specified time period has expired.