Mountain West · ID
How to file Idaho sales tax
2026 due dates, filing frequencies, form 850, and official filing resources.
- State return: 850
- Monthly returns due: 20th of the month following the period
- Filing frequencies: Monthly, Quarterly, Semi-annual, Annual
When is Idaho sales tax due?
Monthly Idaho sales tax returns are due the 20th of the month following the period. Quarterly returns are due the 20th of the month following the period (calendar quarters). When a due date lands on a weekend or federal holiday it moves to the next business day; the 2026 calendar on this page already applies that adjustment.
Idaho sales tax due dates for 2026
Every date below comes from the state's published deadline rule (dataset 2026.07.0) and is already moved to the next business day when it lands on a weekend or federal holiday. Your account's assigned filing frequency decides which table applies.
Monthly Idaho sales tax due dates
Rule: 20th of the month following the period.
| Period | Period ends | Return due |
|---|---|---|
| January 2026 | Jan 31, 2026 | Feb 20, 2026 |
| February 2026 | Feb 28, 2026 | Mar 20, 2026 |
| March 2026 | Mar 31, 2026 | Apr 20, 2026 |
| April 2026 | Apr 30, 2026 | May 20, 2026 |
| May 2026 | May 31, 2026 | Jun 22, 2026 (moved: 2026-06-20 falls on a Saturday) |
| June 2026 | Jun 30, 2026 | Jul 20, 2026 |
| July 2026 | Jul 31, 2026 | Aug 20, 2026 |
| August 2026 | Aug 31, 2026 | Sep 21, 2026 (moved: 2026-09-20 falls on a Sunday) |
| September 2026 | Sep 30, 2026 | Oct 20, 2026 |
| October 2026 | Oct 31, 2026 | Nov 20, 2026 |
| November 2026 | Nov 30, 2026 | Dec 21, 2026 (moved: 2026-12-20 falls on a Sunday) |
| December 2026 | Dec 31, 2026 | Jan 20, 2027 |
Quarterly Idaho sales tax due dates
Rule: 20th of the month following the period (calendar quarters).
| Period | Period ends | Return due |
|---|---|---|
| Q1 2026 | Mar 31, 2026 | Apr 20, 2026 |
| Q2 2026 | Jun 30, 2026 | Jul 20, 2026 |
| Q3 2026 | Sep 30, 2026 | Oct 20, 2026 |
| Q4 2026 | Dec 31, 2026 | Jan 20, 2027 |
- Calendar-quarter mapping inferred from the official 'within 20 days after quarter end' summary — confirm Form 850 instructions.
Semi-annual Idaho sales tax due dates
Rule: 20th of the month following the period (halves: due Jul 20 / Jan 20).
| Period | Period ends | Return due |
|---|---|---|
| January–June 2026 | Jun 30, 2026 | Jul 20, 2026 |
| July–December 2026 | Dec 31, 2026 | Jan 20, 2027 |
Annual Idaho sales tax due dates
Rule: January 20 following the calendar year.
| Period | Period ends | Return due |
|---|---|---|
| Calendar year 2026 | Dec 31, 2026 | Jan 20, 2027 |
Idaho filing notes
No additional state-specific filing notes are recorded for this cadence set.
Return and form
The principal repository-tracked return is 850. A paper channel exists, but the current form version and account eligibility still require confirmation.
Tracked form version: EIN00004 instructions rev 05-20-2025 (blank Form 850 not published — permit-account personalized)
Paper filing posture: accepted
Official Idaho filing resources
File Idaho sales tax from reviewed data, not spreadsheets
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Workflow support does not by itself establish registration, filing authority, credentials, agency acceptance, or tax advice. Confirm your assigned filing frequency with the state.
Idaho sales tax filing questions
When is Idaho sales tax due?
Monthly Idaho sales tax returns are due the 20th of the month following the period. Quarterly returns are due the 20th of the month following the period (calendar quarters). When a due date lands on a weekend or federal holiday it moves to the next business day; the 2026 calendar on this page already applies that adjustment.
How often do you file sales tax in Idaho?
Idaho assigns a filing frequency to each account. The published cadences are monthly, quarterly, semi-annual and annual filing; the state assigns the frequency based on tax volume and notifies the account, so confirm the assigned basis before relying on a calendar.
What form is used to file Idaho sales tax?
The Idaho return tracked here is 850. The principal repository-tracked return is 850. A paper channel exists, but the current form version and account eligibility still require confirmation.
What happens if a Idaho due date falls on a weekend or holiday?
The due date moves to the next business day. In 2026, 3 of the Idaho due dates listed on this page are adjusted for a weekend or federal holiday; each adjusted date is marked in the calendar.
Can Idaho sales tax be filed on paper?
Paper filing posture tracked for Idaho: accepted. The principal repository-tracked return is 850. A paper channel exists, but the current form version and account eligibility still require confirmation.