According to Colorado Department of Revenue , you must file a Colorado return if you were:
- A full-year resident of Colorado, or
- A part-year resident of Colorado with taxable income during that part of the year you were a resident, or
- A nonresident of Colorado with Colorado source income,
- You are required to file a federal income tax return, or
- You have a Colorado income tax liability for the year.
You MUST file using the SAME filing status on both your federal and Colorado income tax returns. Parties to a Civil Union should refer to federal tax law to determine the correct filing status.