Any out of state business that will have ongoing business in the State of Colorado must register with the Colorado Secretary of State. Doing business in Colorado is NOT defined by statute but commonly refers to any business with a physical location in Colorado and/or operation that will extend beyond 30 days.
NOTE: All wages and income earned from work and operations conducted in the State of Colorado are subject to Colorado income tax regardless of the residency of the individual or the business. Employers must withhold Colorado income tax from employee wages and make the required estimated income tax payments for the business. Refer to the Employer Responsibilities and the Income and Property Tax chapters of this guide for more information on filing requirements.
For more information visit https://mybiz.colorado.gov/intro.