Idaho state income tax — ITIN filer guide

Idaho taxes income at a flat 5.3% (tax year 2026), administered by the Idaho State Tax Commission. This guide covers who must file, how filing with an ITIN works, whether the state EITC applies to you, and when refunds arrive.

FLAT rate: 5.3%

  • State return form: Form 40
  • Deadline (tax year 2026): April 15, 2027
  • Who must file: Single under 65: gross income of $15,000 or more (TY2025, Form 40 instructions — tracks federal standard deduction)
  • State sales tax: 6%
  • Special regime: Refundable grocery credit of $155 per person (raised from $120 by HB 231, 2025) offsets sales tax on food; uses the federal standard deduction in computing taxable income
  • Scheduled change: HB 40 (March 2025) cut the flat rate 5.695% to 5.3% retroactive to Jan 1, 2025; legislature has debated going to 5.0% but no further cut confirmed for 2026/2027

Idaho refund timing

  • E-filed returns: about 7-8 weeks after the Tax Commission acknowledges receipt of the e-filed return
  • Paper returns: about 10-11 weeks after the Tax Commission receives the paper return
  • Check your Idaho refund status

State tax agency

  • Idaho State Tax Commission — tax.idaho.gov
  • Phone: (208) 334-7660 / 800-972-7660
  • Free filing option: No state-run e-file for Form 40 — Free File vendors listed at tax.idaho.gov; IRS Direct File (used by ID in 2025) discontinued for the 2026 season

Facts verified 2026-06-11 against official state sources (primary source). Figures refresh with every dataset review.

Filing with an ITIN

Your ITIN is fully accepted on the Idaho state return — states accept the IRS-issued taxpayer number, the same one you use federally. The flow is always the same:

  1. Complete your federal return first (Form 1040 + ITIN)
  2. Transfer your federal figures to Form 40
  3. Apply state-specific deductions and credits
  4. E-file — No state-run e-file for Form 40 — Free File vendors listed at tax.idaho.gov; IRS Direct File (used by ID in 2025) discontinued for the 2026 season
  5. Or visit a VITA site for free in-person preparation

Idaho state EITC — do ITIN filers qualify?

The federal EITC requires valid SSNs for you, your spouse, and qualifying children — ITIN filers can never claim it. What varies is the STATE credit:

Idaho has no state earned income tax credit (EITC). The federal EITC requires a valid SSN — ITIN filers cannot claim it in any state.

State child tax credit: Idaho's $205-per-child Child Tax Credit was scheduled to sunset December 31, 2025, and the 2025 legislature did not extend it — likely unavailable for TY2026 (verify 2026-session action)

See how all 52 jurisdictions compare on the state tax hub and which tax credits ITIN filers can claim.

Last verified: 2026-06-11. Primary source: Idaho State Tax Commission.

General procedural information for educational purposes. Not legal or tax advice. State tax rates change frequently — verify current figures with the state agency before filing. For case-specific guidance, consult a tax professional, enrolled agent, or CPA.