Montana tax deadlines (2025 tax year)
For returns filed in 2026. Different year? See Montana 2026 deadlines →
Montana state deadlines (2025 tax year)
| Individual return (filing) | April 15, 2026 |
|---|---|
| Extended filing deadline | October 15, 2026 |
| Estimated payments | April 15 · June 15 · September 15 · January 15 |
Conforms to the federal deadline; automatic 6-month extension to October 15.
Federal deadlines that still apply (2025 tax year)
| Individual (Form 1040) | April 15, 2026 · extension October 15, 2026 |
|---|---|
| S-corp (1120-S) & partnership (1065) | March 16, 2026 |
| C-corp (Form 1120) | April 15, 2026 |
| Estimated payments | April 15, 2025 · June 16, 2025 · September 15, 2025 · January 15, 2026 |
Frequently asked questions
When are Montana state taxes due for the 2025 tax year?
Montana individual income tax returns for 2025 are due April 15, 2026. If that date falls on a weekend or legal holiday, the deadline moves to the next business day. An extension moves the filing deadline to October 15, but any tax owed is still due on the original date.
Does a Montana extension give me more time to pay?
No. An extension extends the time to file, not to pay. To avoid penalties and interest, pay what you expect to owe by April 15, 2026.
When are Montana estimated tax payments due?
Quarterly estimated payments are generally due April 15, June 15, September 15, January 15. Confirm the current-year dates with the Montana Department of Revenue.
Dates are the standard statutory deadlines for the 2025 tax year and move to the next business day when they fall on a weekend or holiday. Always confirm the current dates with the Montana Department of Revenue or the IRS. This is general information, not tax advice.