Moved from Montana to New Mexico Mid-Year: Which State Tax Returns Do You File?
Answer
You file two part-year returns. Montana taxes the income you received while you lived there, New Mexico taxes the income you received after the move, and each state prorates your deductions and credits to its own slice of the year. The date you changed domicile is the dividing line.
Last verified
A mid-year move splits the tax year in two, and each state taxes its own half. That is a residency question, so the machinery that governs commuters — reciprocity agreements, convenience rules, nonresident withholding — is beside the point here.
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 · New MexicoForm PIT-1 with Schedule PIT-B
File a New Mexico part-year return covering the months you lived in New Mexico. A part-year resident of New Mexico reports the income received while a New Mexico resident, plus any New Mexico-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 | New Mexico | |
|---|---|---|
| Taxes wages | Yes — graduated | Yes — graduated |
| Reciprocity partners | 1 (Form MW-4) | None |
| Convenience rule | No | No |
| Nonresident return | Form 2 with the nonresident/part-year schedule | Form PIT-1 with Schedule PIT-B |
| Part-year return | Form 2 with the nonresident/part-year schedule | Form PIT-1 with Schedule PIT-B |
| Credit for other-state tax | Form 2 (credit for income tax paid to another state) | Form PIT-1 (credit for taxes paid to another state) |
| Nonresident safe harbour | None published | None published |
| Local income tax | No | No |
| Revenue department | Montana Department of Revenue | New Mexico Taxation and Revenue Department |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in New Mexico 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 → New MexicoBoth states — credit offsets the double tax
- Remote worker: Montana → New MexicoHome state only
- 1099 contractor: Montana → New MexicoHome state, plus the client state if you work there
Other Montana pairs
Questions people actually ask
I moved from Montana to New Mexico mid-year. Do I have to file in both states?
You file two part-year returns. Montana taxes the income you received while you lived there, New Mexico taxes the income you received after the move, and each state prorates your deductions and credits to its own slice of the year. The date you changed domicile is the dividing line.
How do I split my income between Montana and New Mexico?
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 New Mexico 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 New Mexico rules on this page were last checked against Montana Department of Revenue and New Mexico Taxation and Revenue Department 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
- New Mexico Taxation and Revenue Department — individual income taxaccessed 2026-08-07