An annuity is a tax deferred insurance product. Income (e.g. interest and dividends) and capital gains earned in an annuity are not taxable until withdrawn. When distributions are made from an annuity, they are reported on a Form 1099-R - It doesn't matter whether the distributions consists of principal, interest, or other earnings. If you received a Form 1099-INT from your bank, it is interest income, and would not be related to an annuity. If you don't know why you received a Form 1099-INT, I suggest you contact the bank or whatever entity it was that issued the Form 1099-INT.