If your business is planning on selling anything, you’ll need a Tax ID number. For Missouri businesses, Tax ID numbers are issued through a Tax Assistance Center with the Missouri Department of Revenue. You can find the contact information to the center nearest you at this link http://dor.mo.gov/tax/assistance.htm
An Employer Identification Number (EIN) is also known as a Federal Tax Identification Number, and is used to identify a business entity. Generally, businesses need an EIN. You may apply for an EIN in various ways, and now you may apply online. This is a free service offered by the Internal Revenue Service. You must check with your state to make sure you need a state number or charter. http://www.irs.gov/businesses/small/article/0,,id=98350,00.html