Key figures
Montana accounting
2026, with sources
Rates and the minimum
Montana taxes corporations at 6.75% of income apportioned to the state, or 7% for a corporation that elects water’s-edge filing instead of worldwide combined reporting. Every corporation owes at least the $50 minimum. A corporation whose only Montana activity is sales, and that owns or rents no property there, may qualify to elect the Alternative Gross Sales tax of 0.5% of Montana sales instead.
The return is Form CIT, due May 15 for a calendar-year corporation — a month after the federal return — with an automatic six-month extension to file but not to pay. Quarterly estimates are required once the corporation expects to owe $5,000 or more.
Apportionment changed in 2025
For tax periods beginning on or after January 1, 2025, Montana apportions business income using the receipts factor alone. From mid-2021 through 2024 it used a double-weighted receipts factor alongside property and payroll; before that, three equal factors. A Delaware startup with one engineer in Bozeman and no Montana customers has little Montana income to apportion under the new rule, even though it files.
Example: a company with $5 million of revenue, $100,000 of it from Montana customers, and a $5 million federal profit apportions 2% of its income to Montana and pays 6.75% on $100,000 — $6,750 — and, having crossed $5,000, makes estimated payments the next year.
Losses
Montana keeps its own NOL rules. A loss from a tax period after 2017 is carried back three years, capped at $500,000 per period, and then forward 10 years. In the provision, a Montana NOL that would expire unused after 10 years needs its own valuation assessment, separate from federal NOLs that carry forward indefinitely.
Deadlines
- May 15 for calendar years; 15th day of the 5th month for fiscal yearsMontana corporate income tax returnForm CIT
- Nov 15Automatic six-month extension to file; tax still due May 15Form CIT (extended)
- QuarterlyQuarterly estimates when the corporation expects to owe $5,000 or moreEstimated tax
The federal baseline
This page covers what Montana adds. The federal rules underneath it apply here too.
Common questions
Can we carry back a Montana loss?
Yes, and it is unusual: Montana still allows a net operating loss from a tax period after 2017 to be carried back three years (up to $500,000 per period) as well as forward 10 years. A company that paid Montana tax in a good year and then loses money can recover some of it; the trade-off is a 10-year carryforward instead of the federal indefinite one.
How does Montana apportion income?
On the receipts factor alone, for tax periods beginning on or after January 1, 2025. Before that Montana used property, payroll and receipts with receipts counted twice. A company with Montana staff but few Montana customers now apportions less income to Montana than it did.
Accounting next door
- IDIdaho accountingIdaho taxes corporations at a flat 5.3% with a $20 minimum, apportions by a single sales factor, and conforms to the Internal Revenue Code as of January 1, 2026, except bonus depreciation.
- NDNorth Dakota accountingNorth Dakota taxes corporate income at 1.41% to 4.31% on three brackets, with no minimum tax. The default is worldwide combined reporting; water’s edge costs a 3.5% surtax.
- SDSouth Dakota accountingSouth Dakota has no corporate income tax, no personal income tax and no gross receipts tax for an ordinary business. Its claim on a startup is sales tax, payroll and the annual report.
- WYWyoming accountingWyoming has no corporate, gross receipts or individual income tax; the only state-level levy on a corporation is the annual report license tax — $60 or $0.0002 per dollar of Wyoming assets.
Founder guides on this
- US GAAPUS GAAP for early-stage startups, in plain EnglishAccrual accounting, revenue recognition (ASC 606), leases (ASC 842), stock compensation and capitalized software: what each means for a small company.
- FundraisingAudit-ready books before your Series AInvestors, lenders and auditors ask for the same things: accrual statements, reconciled accounts and support for every balance. How to be ready first.
More of the Montana guide
- ReceivablesReceivables and sales tax in MontanaSales tax registration, economic nexus, whether SaaS is taxable, and collecting from customers
- PayablesPayables and contractors in MontanaPaying vendors and contractors: 1099 filing, use tax, contractor tests and withholding
- PayrollPayroll taxes and employer rules in MontanaWithholding, unemployment insurance, paid leave, minimum wage and the rules on paydays
- ComplianceCompliance and filings in MontanaRegistering to do business, annual reports, franchise tax and the filing calendar
- AdvisoryAdvisory: credits and decisions in MontanaCredits, incentives and the decisions that are cheaper to get right the first time
Sources
Checked against each agency’s own page on . Rates and thresholds change, usually on January 1.
General information for US companies, not tax, legal or accounting advice for yours. Rules and thresholds change; confirm the specifics with a CPA or the agency before you act on them.