Idaho LLC Tax Deadlines 2026
Complete guide to LLC filing dates, extensions, estimated payment schedules, and required forms in Idaho for the 2026 tax year. Idaho imposes a state income tax, so LLC entities must file both federal and state returns.
Idaho LLC 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
Idaho LLC Tax Calendar at a Glance
| Event | Date |
|---|---|
| Filing deadline | Mar 16, 2026 |
| Extension deadline | Sep 15, 2026 |
FAQ
When is the LLC tax filing deadline in Idaho for 2026?
The Idaho LLC tax return is due Mar 16, 2026 for the 2026 tax year. An extension is available until Sep 15, 2026.
Does Idaho require LLC estimated tax payments?
Estimated payments are not typically required at the entity level for LLC in Idaho, but confirm with Idaho State Tax Commission.
What form do I file for a LLC in Idaho?
LLC entities in Idaho file using Form State business income tax return. You can download the form from Idaho State Tax Commission at https://tax.idaho.gov.
Can I get an extension for my Idaho LLC tax return?
Yes. Idaho allows an extension for LLC 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 Idaho?
Idaho 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 Idaho LLC taxes?
File through Idaho State Tax Commission. Visit https://tax.idaho.gov for e-filing options, downloadable forms, and payment portals.
Idaho Estimated Tax Payments
View the full quarterly estimated payment schedule for Idaho, including all entity types and payment methods.
View Idaho estimated payments →