Illinois state income tax — ITIN filer guide

Illinois taxes income at a flat 4.95% (tax year 2026), administered by the Illinois Department of Revenue. 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: 4.95%

  • State return form: IL-1040
  • Deadline (tax year 2026): April 15, 2027
  • Who must file: Must file if required to file a federal return, or if Illinois base income exceeds the exemption allowance ($2,850 per exemption, TY2025)
  • State sales tax: 6.25%

Illinois refund timing

  • E-filed returns: IDOR: refunds from electronically filed returns expected around 4 weeks after filing
  • Paper returns: IDOR: paper returns may take more than 8 weeks
  • Check your Illinois refund status

State tax agency

  • Illinois Department of Revenue — tax.illinois.gov
  • Phone: 1-800-732-8866
  • Free filing option: MyTax Illinois — free state e-file (IRS Direct File 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 Illinois 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 IL-1040
  3. Apply state-specific deductions and credits
  4. E-file — MyTax Illinois — free state e-file (IRS Direct File discontinued for the 2026 season)
  5. Or visit a VITA site for free in-person preparation

Illinois 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:

Illinois EITC — 20% of the federal EITC (refundable)

✓ OPEN to ITIN filers

IDOR: a valid SSN OR IRS-issued ITIN by the return due date qualifies; expansion effective TY2023 also covers 18-24 and 65+ workers without qualifying children

State child tax credit: Illinois Child Tax Credit = 40% of the filer's IL EITC (TY2025) for dependents under 12; ITIN filers eligible because it piggybacks on the IL EITC

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: Illinois Department of Revenue.

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.