Moved from Montana to Colorado Mid-Year: Which State Tax Returns Do You File?
Answer
Expect a part-year filing on each side. The point of a part-year return is that neither state taxes the whole year, so you are not double-taxed by default — but income received close to the move date has to be assigned carefully, and a lingering Montana source can still pull a nonresident filing along with it.
Last verified
Part-year returns are designed so that neither state taxes the whole year. The risk is not double taxation by default; it is misassigning income received near the move date, and losing the proration on deductions and credits.
What you file
- 1Part-year return · MontanaForm 2 with the nonresident/part-year schedule
File a Montana part-year return covering the months you lived in Montana. A part-year resident of Montana reports the income received while a Montana resident, plus any Montana-source income received during the rest of the year, and prorates the deductions and credits to the residency period.
- 2Part-year return · ColoradoForm DR 0104 with Schedule DR 0104PN
File a Colorado part-year return covering the months you lived in Colorado. A part-year resident of Colorado reports the income received while a Colorado resident, plus any Colorado-source income received during the rest of the year, and prorates the deductions and credits to the residency period.
The two states, side by side
| Montana | Colorado | |
|---|---|---|
| Taxes wages | Yes — graduated | Yes — flat |
| Reciprocity partners | 1 (Form MW-4) | None |
| Convenience rule | No | No |
| Nonresident return | Form 2 with the nonresident/part-year schedule | Form DR 0104 with Schedule DR 0104PN |
| Part-year return | Form 2 with the nonresident/part-year schedule | Form DR 0104 with Schedule DR 0104PN |
| Credit for other-state tax | Form 2 (credit for income tax paid to another state) | Form DR 0104CR |
| Nonresident safe harbour | None published | None published |
| Local income tax | No | Yes |
| Revenue department | Montana Department of Revenue | Colorado Department of Revenue — Taxation Division |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in Colorado and working in Montana gives:Two part-year returns.
Same two states, different situation
The withholding answer turns on how you are paid and where the work happens, not only on which two states are involved.
- W-2 commuter: Montana → ColoradoBoth states — credit offsets the double tax
- Remote worker: Montana → ColoradoHome state only
- 1099 contractor: Montana → ColoradoHome state, plus the client state if you work there
Other Montana pairs
Questions people actually ask
I moved from Montana to Colorado mid-year. Do I have to file in both states?
Expect a part-year filing on each side. The point of a part-year return is that neither state taxes the whole year, so you are not double-taxed by default — but income received close to the move date has to be assigned carefully, and a lingering Montana source can still pull a nonresident filing along with it.
How do I split my income between Montana and Colorado?
By when you received it, measured against the date your domicile actually changed. Income received while you were a Montana resident belongs on the Montana return and income received afterwards on the Colorado return, with each state prorating your deductions, exemptions and credits to its own part of the year. Keep evidence of the move date — a lease, a closing statement, a licence issue date.
How current is this?
The Montana and Colorado rules on this page were last checked against Montana Department of Revenue and Colorado Department of Revenue — Taxation Division on 2026-08-07. We re-check the full grid every December after state legislative sessions close, and re-check the convenience-of-the-employer states quarterly because that is where the rules move fastest.
Sources
Every fact above comes from the revenue department that publishes the rule. We do not cite secondary summaries, and we do not restate a figure we could not find at source.
- Montana Department of Revenue — individual income taxaccessed 2026-08-07
- Colorado Department of Revenue — Taxation Division — individual income taxaccessed 2026-08-07