Missouri requires businesses with employees to register for a withholding tax account (MO Dept of Revenue Tax ID No.)
Missouri prefers employers register online, there is no registration fee.
Follow this link to the Missouri Department of Revenue's registration page and follow the instructions to set up the withholding tax account: https://dor.mo.gov/registerbusiness/index.php
Please note the confirmation number at the end of the application process
After 48 hours, call Missouri at 573-751-5860 to receive the account number over the phone.