In Missouri, In addition to including a completed federal tax form to the state tax form, is it necessary to attach all copies of 1099 forms ?

[HelenaC]

Only if you're mailing in your MO income tax return and only if your W-2's/1099 forms show MO state income tax withheld, on the forms.

• On your W-2, the amount would be in Box 17.
• On your 1099 forms, look for the words, State tax withheld.