Montana business filing dates, 2027

State-level due dates for businesses filing in Montana. Every line links to the official page it came from, with the date that page was read. Where no official source has been verified, the line says so instead of showing a date.

Add to Google Calendar Add to Apple or Outlook Download .ics24 dated lines in the calendar file · sources last read 2026-09-23

Income / franchise tax return

2 dates

The annual return for the business’s tax year, and in franchise-tax states the report that keeps the entity in good standing. Which form and which date depend on the entity type and the tax year. Where the source grants an extension, it extends the time to file; the source says whether it also extends the time to pay.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Pass-through entity return (Form PTE)calendar-year S corporation or partnership Source text “Due Dates Returns March 15 Extensions September 15”verbatim · revenue.mt.gov · retrieved 2026-09-23 “For fiscal filers, Form PTE and tax is due the 15th day of the third month following the close of the entity’s tax year.”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23 “A PTE is granted an automatic extension of time to file of up to six months. An extension of time to file is not an extension to pay.”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23 “File Form PTE and pay the tax due by March 16, 2026.”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23 “A partnership or an S corporation must file a Form PTE annually if the PTE, or one of the DEs it owns: ● has any amount of Montana source income, whether a gain or loss ● filed a return in a prior year and did not mark the return final ● is registered to do business with the Montana Secretary of State ● elects to pay PTET”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23	Applies toA partnership or S corporation with Montana-source income, registered with the Montana Secretary of State, or electing Montana PTET (the preparer attests any one) files Form PTE by March 15 after a calendar year, or the 15th day of the 3rd month after a fiscal year closes. The 2025 instructions move March 15, 2026 (a Sunday) to March 16, so a weekend date is shown on the next business day. An automatic extension of up to six months (September 15 for calendar-year filers) is for filing only. An entity required to file only because it filed a prior-year return is not covered here.	Due ruleForm PTE: 15th day of the 3rd month after the tax year endsA date on a weekend moves to the next business day; state holidays are not compiled.	2027 dates Mar 15MonForm PTEextended: Sep 15 State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.	Source · retrievedrevenue.mt.gov/taxes/pass-through-entities (official source, opens in a new tab)retrieved 2026-09-23revenuefiles.mt.gov/files/Forms/Montana-Form-PTE-Instructions-Booklet/2025_Montana_Form_PTE_Instructions_Booklet.pdf (official source, opens in a new tab)retrieved 2026-09-23
Form CIT corporate income tax returncalendar-year C corporation Source text “Fiscal Year \| 15th day of the 5th month after year-end”verbatim · mtrevenue.gov · retrieved 2026-09-23 “Calendar Year \| May 15”verbatim · mtrevenue.gov · retrieved 2026-09-23 “Montana grants all C corporations an automatic six-month extension to file a return.”verbatim · mtrevenue.gov · retrieved 2026-09-23 “Fiscal Year \| 15th day of the 11th month after year-end”verbatim · mtrevenue.gov · retrieved 2026-09-23 “Extension Deadlines are for Returns Only Any tax liability must still be paid by the original due date or it will be subject to uniform penalties and interest.”verbatim · mtrevenue.gov · retrieved 2026-09-23	Applies toA corporation's Form CIT is due May 15 for calendar-year filers, or the 15th day of the 5th month after a fiscal year ends. An automatic six-month extension (to the 15th day of the 11th month) covers the return only; tax is due by the original date.	Due ruleForm CIT: 15th day of the 5th month after the tax year endsA date on a weekend moves to the next business day; state holidays are not compiled.	2027 dates May 17MonForm CIT · moved from Sat May 15extended: Nov 15 State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.	Source · retrievedmtrevenue.gov/taxes/corporate-income-tax (official source, opens in a new tab)retrieved 2026-09-23

Pass-through entity return (Form PTE)calendar-year S corporation or partnership

Source text

“Due Dates Returns March 15 Extensions September 15”verbatim · revenue.mt.gov · retrieved 2026-09-23

“For fiscal filers, Form PTE and tax is due the 15th day of the third month following the close of the entity’s tax year.”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23

“A PTE is granted an automatic extension of time to file of up to six months. An extension of time to file is not an extension to pay.”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23

“File Form PTE and pay the tax due by March 16, 2026.”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23

“A partnership or an S corporation must file a Form PTE annually if the PTE, or one of the DEs it owns: ● has any amount of Montana source income, whether a gain or loss ● filed a return in a prior year and did not mark the return final ● is registered to do business with the Montana Secretary of State ● elects to pay PTET”verbatim · revenuefiles.mt.gov · retrieved 2026-09-23

Applies toA partnership or S corporation with Montana-source income, registered with the Montana Secretary of State, or electing Montana PTET (the preparer attests any one) files Form PTE by March 15 after a calendar year, or the 15th day of the 3rd month after a fiscal year closes. The 2025 instructions move March 15, 2026 (a Sunday) to March 16, so a weekend date is shown on the next business day. An automatic extension of up to six months (September 15 for calendar-year filers) is for filing only. An entity required to file only because it filed a prior-year return is not covered here.

Due ruleForm PTE: 15th day of the 3rd month after the tax year endsA date on a weekend moves to the next business day; state holidays are not compiled.

2027 dates

Mar 15MonForm PTEextended: Sep 15

State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.

Source · retrievedrevenue.mt.gov/taxes/pass-through-entitiesretrieved 2026-09-23revenuefiles.mt.gov/files/Forms/Montana-Form-PTE-Instructions-Booklet/2025_Montana_Form_PTE_Instructions_Booklet.pdfretrieved 2026-09-23

Form CIT corporate income tax returncalendar-year C corporation

Source text

“Fiscal Year | 15th day of the 5th month after year-end”verbatim · mtrevenue.gov · retrieved 2026-09-23

“Calendar Year | May 15”verbatim · mtrevenue.gov · retrieved 2026-09-23

“Montana grants all C corporations an automatic six-month extension to file a return.”verbatim · mtrevenue.gov · retrieved 2026-09-23

“Fiscal Year | 15th day of the 11th month after year-end”verbatim · mtrevenue.gov · retrieved 2026-09-23

“Extension Deadlines are for Returns Only Any tax liability must still be paid by the original due date or it will be subject to uniform penalties and interest.”verbatim · mtrevenue.gov · retrieved 2026-09-23

Applies toA corporation's Form CIT is due May 15 for calendar-year filers, or the 15th day of the 5th month after a fiscal year ends. An automatic six-month extension (to the 15th day of the 11th month) covers the return only; tax is due by the original date.

Due ruleForm CIT: 15th day of the 5th month after the tax year endsA date on a weekend moves to the next business day; state holidays are not compiled.

2027 dates

May 17MonForm CIT · moved from Sat May 15extended: Nov 15

State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.

Source · retrievedmtrevenue.gov/taxes/corporate-income-taxretrieved 2026-09-23

Estimated tax

8 dates

Installments paid during the year toward the year’s tax. Whether a business must pay them depends on its expected liability, which this page cannot know; the lines show when installments fall due for those who must.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Individual estimated taxcalendar-year Schedule C filer Source text “For Calendar Year Filers: Estimated tax payments are due on these dates: First payment: April 15 Second payment: June 15 Third payment: September 15 Fourth payment: January 15 (of the following year) Please Note: If the due date falls on a weekend or holiday, payments are due on the next business day. For Fiscal Year Filers: Payments are due the 15th day of the: 4th month 6th month 9th month of your fiscal year and the 1st month of the following fiscal year.”verbatim · revenue.mt.gov · retrieved 2026-09-23	Applies toAn individual (including a sole proprietor) paying Montana estimated tax pays by the 15th day of the 4th, 6th and 9th months of the tax year and the 1st month after it (April 15, June 15, September 15, January 15 for calendar-year filers); a weekend or holiday date moves to the next business day.	Due rule1st payment: 15th day of the 4th month of the tax year; 2nd payment: 15th day of the 6th month of the tax year; 3rd payment: 15th day of the 9th month of the tax year; 4th payment: 15th day of the month after the tax year endsA date on a weekend moves to the next business day; state holidays are not compiled.	2027 dates Jan 15Fri4th payment Apr 15Thu1st payment Jun 15Tue2nd payment Sep 15Wed3rd payment State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.	Source · retrievedrevenue.mt.gov/taxes/estimated-tax-payments (official source, opens in a new tab)retrieved 2026-09-23
Corporate estimated taxcalendar-year C corporation Source text “Estimated payments are due on the 15th of the fourth, sixth, ninth, and twelfth months of your tax year.”verbatim · mtrevenue.gov · retrieved 2026-09-23 “If your business estimates owing $5,000 or more, you will need to make quarterly estimated tax payments.”verbatim · mtrevenue.gov · retrieved 2026-09-23	Applies toA corporation estimating $5,000 or more of tax pays quarterly estimates by the 15th day of the 4th, 6th, 9th and 12th months of its tax year (April 15, June 15, September 15, December 15 for calendar-year filers). The page states its weekend rule for returns only, so estimate dates are shown as stated.	Due rule1st estimate: 15th day of the 4th month of the tax year; 2nd estimate: 15th day of the 6th month of the tax year; 3rd estimate: 15th day of the 9th month of the tax year; 4th estimate: 15th day of the 12th month of the tax year	2027 dates Apr 15Thu1st estimate Jun 15Tue2nd estimate Sep 15Wed3rd estimate Dec 15Wed4th estimate	Source · retrievedmtrevenue.gov/taxes/corporate-income-tax (official source, opens in a new tab)retrieved 2026-09-23

Individual estimated taxcalendar-year Schedule C filer

Source text

“For Calendar Year Filers: Estimated tax payments are due on these dates: First payment: April 15 Second payment: June 15 Third payment: September 15 Fourth payment: January 15 (of the following year) Please Note: If the due date falls on a weekend or holiday, payments are due on the next business day. For Fiscal Year Filers: Payments are due the 15th day of the: 4th month 6th month 9th month of your fiscal year and the 1st month of the following fiscal year.”verbatim · revenue.mt.gov · retrieved 2026-09-23

Applies toAn individual (including a sole proprietor) paying Montana estimated tax pays by the 15th day of the 4th, 6th and 9th months of the tax year and the 1st month after it (April 15, June 15, September 15, January 15 for calendar-year filers); a weekend or holiday date moves to the next business day.

Due rule1st payment: 15th day of the 4th month of the tax year; 2nd payment: 15th day of the 6th month of the tax year; 3rd payment: 15th day of the 9th month of the tax year; 4th payment: 15th day of the month after the tax year endsA date on a weekend moves to the next business day; state holidays are not compiled.

2027 dates

Jan 15Fri4th payment
Apr 15Thu1st payment
Jun 15Tue2nd payment
Sep 15Wed3rd payment

State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.

Source · retrievedrevenue.mt.gov/taxes/estimated-tax-paymentsretrieved 2026-09-23

Corporate estimated taxcalendar-year C corporation

Source text

“Estimated payments are due on the 15th of the fourth, sixth, ninth, and twelfth months of your tax year.”verbatim · mtrevenue.gov · retrieved 2026-09-23

“If your business estimates owing $5,000 or more, you will need to make quarterly estimated tax payments.”verbatim · mtrevenue.gov · retrieved 2026-09-23

Applies toA corporation estimating $5,000 or more of tax pays quarterly estimates by the 15th day of the 4th, 6th, 9th and 12th months of its tax year (April 15, June 15, September 15, December 15 for calendar-year filers). The page states its weekend rule for returns only, so estimate dates are shown as stated.

Due rule1st estimate: 15th day of the 4th month of the tax year; 2nd estimate: 15th day of the 6th month of the tax year; 3rd estimate: 15th day of the 9th month of the tax year; 4th estimate: 15th day of the 12th month of the tax year

2027 dates

Apr 15Thu1st estimate
Jun 15Tue2nd estimate
Sep 15Wed3rd estimate
Dec 15Wed4th estimate

Source · retrievedmtrevenue.gov/taxes/corporate-income-taxretrieved 2026-09-23

Withholding

14 dates · 1 not dated yet

Returns and deposits of income tax withheld from employees’ wages. The agency assigns each employer a deposit frequency, usually from its past liability, so the dates differ by frequency.

Why no dates: Every date shown here is checked against its official source.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Wage withholding paymentsmonthly withholding filer Source text “$1,200—$11,999 \| Monthly \| The 15th of the following month. Example: January withholding is due February 15.”verbatim · revenue.mt.gov · retrieved 2026-09-23 “Up to $1,199 \| Annual \| January 31”verbatim · revenue.mt.gov · retrieved 2026-09-23 “$12,000 or more \| Accelerated \| Same as federal tax deposits: Paydays Saturday–Tuesday: due the following Friday Paydays Wednesday–Friday: due the following Wednesday”verbatim · revenue.mt.gov · retrieved 2026-09-23	Applies toPayment schedule by total withholding: up to $1,199 annual, by January 31; $1,200 to $11,999 monthly, by the 15th of the following month; $12,000 or more accelerated, on the federal semiweekly schedule.	Due ruleMonthly withholding payment: 15th day of the month after the month ends	2027 dates Jan 15FriMonthly withholding payment Feb 15MonMonthly withholding payment Mar 15MonMonthly withholding payment Apr 15ThuMonthly withholding payment May 15Sat†Monthly withholding payment Jun 15TueMonthly withholding payment Jul 15ThuMonthly withholding payment Aug 15Sun†Monthly withholding payment Sep 15WedMonthly withholding payment Oct 15FriMonthly withholding payment Nov 15MonMonthly withholding payment Dec 15WedMonthly withholding payment † Falls on a Saturday; the source states no weekend rule. Falls on a Sunday; the source states no weekend rule.	Source · retrievedrevenue.mt.gov/taxes/withholding-tax/wage-withholding-returns-and-payments (official source, opens in a new tab)retrieved 2026-09-23
Wage withholding paymentsannual withholding filer Source text “$1,200—$11,999 \| Monthly \| The 15th of the following month. Example: January withholding is due February 15.”verbatim · revenue.mt.gov · retrieved 2026-09-23 “Up to $1,199 \| Annual \| January 31”verbatim · revenue.mt.gov · retrieved 2026-09-23 “$12,000 or more \| Accelerated \| Same as federal tax deposits: Paydays Saturday–Tuesday: due the following Friday Paydays Wednesday–Friday: due the following Wednesday”verbatim · revenue.mt.gov · retrieved 2026-09-23	Applies toPayment schedule by total withholding: up to $1,199 annual, by January 31; $1,200 to $11,999 monthly, by the 15th of the following month; $12,000 or more accelerated, on the federal semiweekly schedule.	Due ruleAnnual withholding payment: January 31 of the year after the calendar year ends	2027 dates Jan 31SunAnnual withholding payment Falls on a Sunday; the source states no weekend rule.	Source · retrievedrevenue.mt.gov/taxes/withholding-tax/wage-withholding-returns-and-payments (official source, opens in a new tab)retrieved 2026-09-23
Annual W-2/1099 withholding reconciliation (MW-3) Source text “Montana Annual W-2 1099 Withholding Tax Reconciliation (Form MW-3) \| January 31”verbatim · revenue.mt.gov · retrieved 2026-09-23 “All Forms W-2 (with or without withholding) \| January 31”verbatim · revenue.mt.gov · retrieved 2026-09-23 “Forms 1099 with Withholding \| January 31”verbatim · revenue.mt.gov · retrieved 2026-09-23 “If the due date falls on a weekend, the form is due the next business day.”verbatim · revenue.mt.gov · retrieved 2026-09-23 “Every year that you have an open Montana withholding account, you must file a Montana Annual W-2 1099 Withholding Tax Reconciliation - Form MW-3 (PDF) return.”verbatim · revenue.mt.gov · retrieved 2026-09-23	Applies toAn employer with an open Montana withholding account (the preparer declares the Montana withholding filing schedule the Department assigned it) files the MW-3 annual reconciliation every year, with all Forms W-2 and the Forms 1099 showing Montana withholding, by January 31; a weekend due date moves to the next business day. An employer that has not declared a Montana withholding schedule is not dated by this line.	Due ruleForm MW-3: January 31 of the year after the calendar year endsA date on a weekend moves to the next business day; state holidays are not compiled.	2027 dates Feb 1MonForm MW-3 · moved from Sun Jan 31 State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.	Source · retrievedrevenue.mt.gov/taxes/withholding-tax/wage-withholding-returns-and-payments (official source, opens in a new tab)retrieved 2026-09-23
Wage withholding paymentssemiweekly withholding filer Source text “$1,200—$11,999 \| Monthly \| The 15th of the following month. Example: January withholding is due February 15.”verbatim · revenue.mt.gov · retrieved 2026-09-23 “Up to $1,199 \| Annual \| January 31”verbatim · revenue.mt.gov · retrieved 2026-09-23 “$12,000 or more \| Accelerated \| Same as federal tax deposits: Paydays Saturday–Tuesday: due the following Friday Paydays Wednesday–Friday: due the following Wednesday”verbatim · revenue.mt.gov · retrieved 2026-09-23	Applies toPayment schedule by total withholding: up to $1,199 annual, by January 31; $1,200 to $11,999 monthly, by the 15th of the following month; $12,000 or more accelerated, on the federal semiweekly schedule.	Due ruleAccelerated withholding payment: payday on Wednesday, Thursday or Friday: the following Wednesday; payday on Saturday through Tuesday: the following Friday	2027 datesOne date per payday; not in the .ics	Source · retrievedrevenue.mt.gov/taxes/withholding-tax/wage-withholding-returns-and-payments (official source, opens in a new tab)retrieved 2026-09-23
Wage withholding paymentssemiweekly withholding filer	Applies toPayment schedule by total withholding: up to $1,199 annual, by January 31; $1,200 to $11,999 monthly, by the 15th of the following month; $12,000 or more accelerated, on the federal semiweekly schedule.	Due ruleUnsupported	2027 datesNot dated until the client's profile answers: pay cadence.	Source · retrievedNo verified source on file

Unemployment insurance

Unsupported

Employer contribution and wage reports for unemployment insurance: the state program, and FUTA at the federal level.

Why no dates: No official source confirmed yet for Montana's unemployment insurance report due dates.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Unemployment insurance	Applies toShown once verified	Due ruleUnsupported	2027 datesNo official source confirmed yet for Montana's unemployment insurance report due dates.	Source · retrievedNo verified source on file

Sales and use tax

no fixed date

Returns for sales and use tax collected under a permit. The agency assigns each permit holder a filing frequency; the dates differ by frequency.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
No Montana general sales tax Source text “Montana does not have a general-use sales tax.”verbatim · mtrevenue.gov · retrieved 2026-09-23	Applies toMontana has no general sales tax.	Due ruleNo date: see the source text	2027 dates—	Source · retrievedmtrevenue.gov/taxes/general-sales-tax (official source, opens in a new tab)retrieved 2026-09-23

Annual report

Unsupported

The annual or biennial report an entity files with the Secretary of State (or its equivalent) to stay in good standing. Some are keyed to the month the entity was formed.

Why no dates: No official source confirmed yet for Montana's annual report due date.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Annual report	Applies toShown once verified	Due ruleUnsupported	2027 datesNo official source confirmed yet for Montana's annual report due date.	Source · retrievedNo verified source on file

Due-date rules

no fixed date

The conventions other lines cite: how a date on a weekend or holiday moves, and how a disaster declaration postpones deadlines.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Weekend and holiday due dates Source text “If the deadline falls on a weekend or holiday, the return is due the next business day.”verbatim · mtrevenue.gov · retrieved 2026-09-23	Applies toA Montana corporate return deadline on a weekend or holiday moves to the next business day.	Due ruleNo date: see the source text	2027 dates—	Source · retrievedmtrevenue.gov/taxes/corporate-income-tax (official source, opens in a new tab)retrieved 2026-09-23

Dates are computed from the linked pages as they read on each retrieval date. Agencies change their pages, and the IRS postpones deadlines after disasters; confirm with the source before filing.

Tracking these for a list of clients? FilingDates builds each client’s calendar from the same rules, with every date linked to its source.