You may well have a situation of dual residency.
You're definitely a domiciliary resident of Michigan, since that's your main or primary home. But Colorado considers someone a resident by statute if:
(i) The person maintains a permanent place of abode in Colorado, and
(ii) Spends, in the aggregate, more than six months of the taxable year in Colorado.
You'll find Colorado's law and definitions here:
Dual residents must file as a resident in each of the two states, but generally the domiciliary state will allow a credit for the taxes paid to the statutory resident state.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
