Edited: (even more details)
If your printed form has a 2D barcode on it......Page 2 of the MO instructions (bottom of left column) has several addresses ...based on whether you are getting a refund, or are having to pay a balance due
https://dor.mo.gov/forms/MO-1040%20Instructions_2019.pdf
_______________________________
If your printed form does not have a 2D barcode on it......Page 4 of the MO instructions (left column) has several addresses ...based on whether you are getting a refund, or are having to pay a balance due
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
