Log onto IRS.gov and fill out an Employer Identification Number application. Once you have completed the application, the site will verify the information and immediately issue you an EIN.
Log onto Missouri's Department of Revenue at http://dor.mo.gov/tax/business/register/forms/ and print a Missouri tax registration application, also known as Form 2643A. The application is approximately four pages long and requires you to provide general information about your business.
Complete the Missouri tax registration application and mail it to the Missouri Department of Revenue at P.O. Box 357, Jefferson City, MO 65105-0357. Once the Missouri Department of Revenue has received your application, a representative will review it and issue your business a tax identification number within one to two weeks.