Actually, returns with a payment due and a 2-D barcode should be sent to P.O. Box 3370, Jefferson City, MO 65105-3370. See 2-D BARCODE RETURNS in the Instructions for Form MO-1040 for more information.
For non-barcode returns, the address to send a balance-due return is P.O. Box 329, Jefferson City, MO 65105-0329. See WHERE TO MAIL YOUR RETURN in the link above.
