A MITS/MO ID number is assigned to all corporations registered with the Missouri Department of Revenue. This number is used to locate financial information associated with the corporation. This includes original returns, estimated tax payments, Form MO-7004 payments, etc. Every Form MO-1120 filed must have a MITS/MO ID number on it. A return without this number or one with an incorrect number may cause a delay in processing. If you do not have a MITS number, or need to locate the MITS number, an officer may call the Missouri Department of Revenue, Business Tax Registration at (573) 751-5860.