Colorado Tax Residency (183-day rule)

Key parameters
Threshold	6 months (~183 days)
Period / Window	Tax year (1 Jan – 31 Dec)
Counting	Any part of a day
Alternative	Domicile
Additional requirements	Permanent place of abode

This applies to anyone with a home available to them in Colorado, whichever state they treat as their own. You are a Colorado resident if either of these applies:

• Domicile — Colorado is your permanent home, the place you intend to return to whenever you are away.
• Statutory residency — you maintain a permanent place of abode in Colorado and spend more than 6 months of the tax year in the state.

The second route asks nothing about intent. A home and a count are the whole of it, which is why it catches people who think of themselves as visiting rather than living there. You need not own the abode, and the rule applies even where you are domiciled in another state.

• Two separate seasons add together. Because the time need not be consecutive, a winter in the mountains and a summer in the same house combine into one total.
• Owning the abode is not required. A rented or otherwise available permanent place of abode satisfies the limb as fully as one you hold title to.
• No day is exempt. Weekends, holidays and travel days all count the same as working days.
• A second home is enough for the abode limb. The test asks whether a permanent place of abode is maintained, not whether it is your main residence.
• Two states can tax the same year as a resident year. Statutory residency here leaves your domicile elsewhere intact, with credits closing only part of the overlap.
• Domicile carries no threshold. Someone domiciled in Colorado is a resident on that basis alone, whatever their count.

A resident is taxed on income from all sources while a nonresident pays only on Colorado-source income, so an error usually surfaces as out-of-state earnings never reported while another state taxed the same income. The Department charges interest from the original due date and adds penalties for filing late and for underpaying, with greater exposure where an understatement is treated as deliberate. Professional tax advice is strongly recommended in situations like this.

A mountain house across two seasons

You are domiciled in Texas and own a house near Vail, spending about 120 days there over winter and another 80 across summer. The days add together past 183 with the abode maintained, so you are a Colorado statutory resident.

Remote work from a rented condo

You rent a Denver condo for the year while working remotely for an out-of-state employer, spending roughly 250 days in Colorado. Both limbs hold and residency follows regardless of where your employer sits.

A ski season and nothing more

You own the same mountain house but use it only for a 90-day winter season. The abode limb holds while the count falls short of 183, so residency does not attach.

• Colorado Department of Revenue — Income tax topics, part-year residents and nonresidents
• Colorado Department of Revenue — Individual income tax