Montana (MT)
April 15, 2026
October 15, 2026
✓ Automatic
MT — MontanaMontana Personal Income Tax Extension — What You Need to Do
Montana automatically grants a six-month extension to October 15, 2026 — you don’t need to submit a form for the extension, and it applies whether or not you have a federal extension. The only thing that matters is paying your tax liability by April 15, 2026 to avoid penalties and interest.
Montana Extension Checklist — 2026
Two things to handle. No Montana extension form to file — the extension is automatic.
April 15, 2026
Pay Any Montana Tax Due
Bank Account via Montana TAP
Montana TransAction Portal (TAP)
Make an extension payment electronically without mailing anything.
October 15, 2026
File Federal + Montana Return
File your federal return now and add your Montana state return — Form 2 — in the same session. No extension form or federal extension copy is required. Filing sooner means a faster refund. Your Montana extended deadline is October 15.
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Montana Late Filing & Payment Penalties — What It Costs to Wait
Because the extension is automatic, the late-filing penalty only applies if you miss the extended October 15 deadline — the late-payment penalty and interest apply separately to any unpaid balance.
| Charge Type | Rate | Cap | Trigger |
|---|---|---|---|
| Late Filing Penalty | Greater of $50 or 5% of unpaid tax per month | 25% | Return filed after October 15, 2026 |
| Late Payment Penalty | 0.5% of unpaid tax per month | 12% | Tax unpaid after April 15, 2026 |
| Interest | 7% per year (2026), 0.019178% daily | No cap | Accrues from April 15 on any unpaid balance |
Montana State Extension Details
| Extension Type | Automatic — No Form, Independent of Federal Extension |
| Original Filing Deadline | April 15, 2026 |
| Extended Filing Deadline | October 15, 2026 |
| Extension Period | 6 months |
| Extension Form | None — Montana does not require a form for the extension |
| Return Form | Form 2 (Montana Individual Income Tax Return) |
| Federal Extension Required? | No — Montana’s extension is automatic and independent of federal extension status |
| Payment Deadline | April 15, 2026 (extension does not extend time to pay) |
| Payment Voucher | Form IT (Montana Individual Income Tax Payment Voucher) — for mailed extension payments only |
| Online Payment Portal | Montana TransAction Portal (TAP) |
| Extension Payment Mailing Address | Montana Department of Revenue, PO Box 6309, Helena, MT 59604-6309 |
| Return Mailing Address (refund/no tax due) | Montana Department of Revenue, PO Box 6577, Helena, MT 59604-6577 |
| Return Mailing Address (payment enclosed) | Montana Department of Revenue, PO Box 6308, Helena, MT 59604-6308 |
| State Agency | Montana Department of Revenue |
| Late Filing Penalty | Greater of $50 or 5% of unpaid tax per month, up to 25% |
| Late Payment Penalty | 0.5% of unpaid tax per month, up to 12% |
| Interest Rate (2026) | 7% per year (0.019178% daily) |
Montana Tax Extension — Frequently Asked Questions
Do I need to file a Montana extension form?
No. Montana grants an automatic six-month extension with no form required — you automatically have until October 15 to file, regardless of your federal extension status.
Does a federal extension matter for Montana?
No. Montana’s automatic extension applies regardless of whether you have a federal extension — the two are independent of each other.
What is Form IT for?
Form IT is Montana’s individual income tax payment voucher, used to mail an extension or estimated payment by check. It’s not an extension request — you can also pay through Montana’s TAP portal without it.
What if I’m due a refund?
If you’re due a refund, there’s no tax owed, so there’s no payment penalty for filing later within the automatic extension window. You’ll still want to file as soon as possible to get your refund.
Which Montana return form do I need?
Form 2 is Montana’s individual income tax return, used by residents, part-year residents, and nonresidents alike.
Where do I mail my payment versus my return?
Extension and estimated payments (Form IT) go to PO Box 6309. Completed returns go to PO Box 6577 (refund/no tax due) or PO Box 6308 (payment enclosed) — three different addresses depending on purpose.
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File your federal return and add Montana state in the same session. October 15 extended deadline — secure, fast, with live support.