Opening a Business in Missouri
Welcome to Missouri, a great place to do business. If you are already incorporated in another state and want to open a branch office or do work in Missouri, here is valuable information. You can also check out the Missouri Secretary of State's FAQs regarding doing business in Missouri.
Registering as a foreign entity
The forms to register as a foreign entity can be found on the Missouri Secretary of State's website.
Corporations: Application for Certificate of Authority for a Foreign For-Profit Corporation (Corp. 42)
Limited Liability Company: Application for Registration of a Foreign Limited Liability Company (LLC 4)
Limited Partnership: Application for Registration of a Foreign Limited Partnership in Missouri (LP 42)
Limited Liability Limited Partnership: Application for Registration of a Foreign Limited Liability Limited Partnership in Missouri (LP 25)
Transient Employer License
Out of state companies who temporarily transact any business in the state of Missouri are defined as transient employers and are required to register, file a bond and remit withholding tax to the Missouri Department of Revenue. Refer to the following link for more information on this and exemption criteria: www.dor.mo.gov/tax/business/register/forms/3032f.pdf.
Register for Withholding Tax (Transient Employer - Bond required) and Missouri Corporate Income Tax (if a corporation). Form 2643: www.dor.mo.gov/tax/business/register/forms/2643af.pdf 
Should you have any questions pertaining to the Transient Employer License you may also contact their office by telephone at: (573) 751-0459.
Local business licenses
Business licenses are done at the local level. Some cities and counties require transient employees to obtain business licenses. To find the phone number of the city/county office go to http://www.business.mo.gov/lookup/CityCounty_Search.aspx.