Montana — Personal Income Tax

Montana requires an individual income tax return if you were a Montana resident, part-year resident, or nonresident with Montana source income during the tax year, and you were required to file a federal income tax return under the Internal Revenue Code. Even if you are not required to file a federal return, you must file a Montana return if you have Montana taxable income after applying the Montana-specific additions and subtractions to federal taxable income.

Certain nonresidents may qualify for a filing exclusion. Nonresidents who earned only wages for services performed in Montana for 30 days or fewer and who worked in more than one state during the tax year do not have to file or pay Montana tax on that income, unless they have other Montana source income. This exclusion does not apply to self-employed individuals.

Source: Mont. Code Ann. § 15-30-2602 | Montana DOR, Individual Filing Requirements

For tax year 2026, Montana imposes a two-bracket graduated tax on ordinary income (taxable income other than net long-term capital gains). The rate is 4.7% on Montana taxable income up to $95,000 for married filing jointly and qualifying surviving spouses, up to $71,250 for heads of household, and up to $47,500 for single filers, married filing separately, estates, and trusts. Income above those thresholds is taxed at 5.65%. These rates became effective January 1, 2026.

Source: Mont. Code Ann. § 15-30-2103 | Montana DOR, 2026 Withholding Updates

For tax year 2026, Montana taxes net long-term capital gains separately from ordinary income at preferential rates of 3.0% and 4.1%. For married filing jointly and qualifying surviving spouses, the rate is 3.0% on the first $95,000 less nonqualified taxable income of net long-term capital gains, and 4.1% on amounts exceeding that threshold. If nonqualified taxable income (ordinary income) is $95,000 or greater, all net long-term capital gains are taxed at 4.1%. For heads of household, the 3.0% rate applies to the first $71,250 less nonqualified taxable income; for single filers, married filing separately, estates, and trusts, the threshold is $47,500 less nonqualified taxable income. Net long-term capital gains are defined by reference to IRC § 1222.

Source: Mont. Code Ann. § 15-30-2103 | Montana DOR, HB337: 2026–2027 Individual Income Tax Changes

Montana determines taxable income by starting with federal taxable income and applying Montana-specific additions and subtractions. Montana does not have a separate state standard deduction; the federal standard deduction is already reflected in federal taxable income before Montana's calculation begins. This method has been in effect since tax year 2024, when Montana repealed its prior 20%-of-AGI state standard deduction and eliminated itemized deduction provisions that previously existed under former Mont. Code Ann. § 15-30-2131 and § 15-30-2132.

Source: Mont. Code Ann. § 15-30-2120

Montana classifies individuals for income tax purposes as residents, part-year residents, or nonresidents. The classification determines the scope of income subject to Montana tax: residents are taxed on all income regardless of source; part-year residents are taxed on all income received while a Montana resident plus Montana-source income received while a nonresident; nonresidents are taxed only on Montana-source income.

Resident. Mont. Code Ann. § 15-30-2101(31) defines "resident" as any natural person who is (1) domiciled in Montana, or (2) maintains a permanent place of abode within Montana even though temporarily absent from the state and who has not established a residence elsewhere. Either prong suffices for resident status.

"Domiciled" means having a residence in Montana as stated in Mont. Code Ann. § 1-1-215, which defines domicile as the place where an individual has a true, fixed, principal, and permanent home and to which the individual intends to return whenever absent. "Permanent place of abode" is defined in Mont. Admin. r. 42.15.107(2) as "a dwelling place habitually used by an individual as the individual's home, whether or not owned by the individual or a dwelling the individual may someday leave."

Mont. Admin. r. 42.15.109(1) provides that whether an individual is a Montana resident "is determined in light of all facts and circumstances." The Montana Department of Revenue states that if an individual maintains a place of abode in both Montana and another state, and both show similar permanency characteristics, the department may look at "whether the individual has abandoned residency in one state in favor of another state through affirmative actions." The DOR cites as examples of factors indicating Montana residency: Montana voter registration, Montana resident hunting and fishing licenses, and a Montana driver's license.

Part-year resident. The Montana DOR defines a part-year resident as an individual who either (1) was a Montana resident at the start of the year and then established residency in another state during the year, or (2) was a nonresident at the start of the year and then established residency in Montana during the year. This requires an actual change of residency status with the intention of establishing a permanent residence in the new state.

The DOR clarifies that the following individuals are not part-year residents: (a) retirees (commonly called "snowbirds") who are residents of Montana but live in another state for a portion of each year; (b) a resident of another state who works in Montana on a seasonal basis but does not establish residency in Montana; and (c) a Montana resident attending an out-of-state college who has not established residency elsewhere.

Nonresident. Mont. Code Ann. § 15-30-2101(23) defines a "nonresident" as a natural person who is not a resident. A nonresident is taxed only on Montana-source income. Section 15-30-2101(21) defines Montana-source income to include, among other items, wages for services performed in Montana, income from property located in Montana, and income from a business conducted in Montana.

Special rules for military personnel. Mont. Admin. r. 42.15.109(2) provides that a Montana resident who enters the U.S. armed forces does not lose Montana resident status solely by reason of being absent from the state in compliance with military orders. Conversely, Mont. Admin. r. 42.15.112(1) provides that a nonresident member of the armed forces who is living in Montana solely by reason of compliance with military orders does not become a Montana resident solely by being present in the state, and their compensation for military service is not Montana-source income. The DOR guidance explains that under the federal Military Spouses Residency Relief Act, starting in 2009, some nonresident spouses who move to Montana solely to be with a nonresident serviceperson are also allowed to retain their home residence or domicile and, subject to certain rules and limitations, their wage and other personal services income is not Montana-source income.

Source: Mont. Code Ann. § 15-30-2101 | Mont. Admin. r. 42.15.109 | Mont. Admin. r. 42.15.107 | Mont. Admin. r. 42.15.112 | Montana DOR, Residency

Montana individual income tax returns are due on or before April 15 following the close of the calendar year. For fiscal-year filers, the return must be filed on or before the 15th day of the 4th month following the close of the taxpayer's fiscal year. This deadline is established by Mont. Code Ann. § 15-30-2604(1)(a).

Holiday deferral. If the April 15 due date falls on a holiday that defers a filing date as recognized by the Internal Revenue Service but that is not observed in Montana, the return may be made on the first business day after the holiday. Mont. Code Ann. § 15-30-2604(1)(b)(i).

Automatic six-month extension. Montana grants an automatic extension of time for filing of up to six months following the prescribed due date. Mont. Code Ann. § 15-30-2604(3)(a). For calendar-year filers, this moves the extended deadline to October 15. Montana does not require taxpayers to file a separate extension form or request — the extension is automatic.

Extension is for filing only, not payment. The extension of time for filing a return is not an extension of time for payment of taxes. Mont. Code Ann. § 15-30-2604(5). All tax due must be paid by the original April 15 deadline (or the applicable fiscal-year deadline). Any tax not paid by the original deadline is subject to penalty and interest as provided in Mont. Code Ann. § 15-1-216. Mont. Code Ann. § 15-30-2604(3)(b).

Disaster relief. The Montana Department of Revenue may extend filing dates and defer or waive interest, penalties, and other late-filing consequences for a period not exceeding one year for taxpayers affected by a federally declared disaster or a terroristic or military action recognized for federal tax purposes under 26 U.S.C. § 7508A. Mont. Code Ann. § 15-30-2604(1)(b)(ii). Additionally, the department may grant an additional extension of time for filing a return whenever in its judgment good cause exists. Mont. Code Ann. § 15-30-2604(4).

Source: Mont. Code Ann. § 15-30-2604