Generally, tax-exempt interest and dividend income is usually reported on year-end statements or a statement from your broker or mutual fund company; it's usually listed on the last pages of the statement.
If you have earned tax exempt dividends in more than one state and the amount is insignificant, you may select "more than one state".
See attached picture.
Note - if you have an electronic error and are looking for a specific code for "more than one state", you can enter "XX".
