Montana Partnership Tax Deadlines 2026
Complete guide to Partnership filing dates, extensions, estimated payment schedules, and required forms in Montana for the 2026 tax year. Montana imposes a state income tax, so Partnership entities must file both federal and state returns.
Montana Partnership filing deadline
Calendar-year due date follows federal timing for pass-through entities.
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State business income tax return
Estimated payments
No state estimated payment schedule listed.
Due: N/A
Montana Partnership Tax Calendar at a Glance
| Event | Date |
|---|---|
| Filing deadline | Mar 16, 2026 |
| Extension deadline | Sep 15, 2026 |
FAQ
When is the Partnership tax filing deadline in Montana for 2026?
The Montana Partnership tax return is due Mar 16, 2026 for the 2026 tax year. An extension is available until Sep 15, 2026.
Does Montana require Partnership estimated tax payments?
Estimated payments are not typically required at the entity level for Partnership in Montana, but confirm with Montana Department of Revenue.
What form do I file for a Partnership in Montana?
Partnership entities in Montana file using Form State business income tax return. You can download the form from Montana Department of Revenue at https://mtrevenue.gov.
Can I get an extension for my Montana Partnership tax return?
Yes. Montana allows an extension for Partnership returns until Sep 15, 2026. Note that an extension gives you more time to file, not more time to pay — any tax owed is still due by the original deadline of Mar 16, 2026.
What are the penalties for filing late in Montana?
Montana typically charges a failure-to-file penalty (usually 5% of unpaid tax per month, up to 25%) and a failure-to-pay penalty (usually 0.5-1% per month). Interest also accrues on unpaid balances. Filing for an extension by the original deadline avoids the failure-to-file penalty but not the failure-to-pay penalty.
Where can I file Montana Partnership taxes?
File through Montana Department of Revenue. Visit https://mtrevenue.gov for e-filing options, downloadable forms, and payment portals.
Montana Estimated Tax Payments
View the full quarterly estimated payment schedule for Montana, including all entity types and payment methods.
View Montana estimated payments →