Oklahoma state income tax — ITIN filer guide

Oklahoma uses a graduated income tax from 0% to 4.5% (tax year 2026), administered by the Oklahoma 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.

GRADUATED: 0% – 4.5% · 3 brackets

  • State return form: Form 511 (Oklahoma Resident Individual Income Tax Return)
  • Deadline (tax year 2026): April 15, 2027 (paper); extended to April 20, 2027 if you file electronically
  • Who must file: Residents generally must file an Oklahoma return if they were required to file a federal return; exact gross-income tests in the Form 511 instructions packet.
  • State sales tax: 4.5%
  • Scheduled change: HB 2764 (signed May 28, 2025): from TY2026, top rate cut 4.75% -> 4.5% and six brackets consolidated to three (0% on first $3,750 single / $7,500 joint; top 4.5% from $7,200 single); further automatic 0.25-point cuts toward full phase-out when revenue triggers are met.

Oklahoma refund timing

  • E-filed returns: OTC infographic: file online with direct deposit — refund in about 5 to 6 weeks (begin checking status ~4 business days after acceptance).
  • Paper returns: Paper filers typically wait about 10 to 13 weeks; wait ~3 weeks before checking status.
  • Check your Oklahoma refund status

State tax agency

  • Oklahoma Tax Commission — oklahoma.gov/tax
  • Phone: (405) 521-3160 / (800) 522-8165 (in-state)
  • Free filing option: None verified — commercial software or VITA (Oklahoma was an IRS Direct File state, but Direct File is discontinued from filing season 2026); refund status free via OkTAP.

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 Oklahoma 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 511 (Oklahoma Resident Individual Income Tax Return)
  3. Apply state-specific deductions and credits
  4. E-file — None verified — commercial software or VITA (Oklahoma was an IRS Direct File state, but Direct File is discontinued from filing season 2026); refund status free via OkTAP.
  5. Or visit a VITA site for free in-person preparation

Oklahoma 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:

Oklahoma Earned Income Credit — 5% (computed using federal EITC rules as in effect for tax year 2020) of the federal EITC (refundable)

✗ SSN required (not available to ITIN filers)

Refundable again beginning TY2022. Requires qualifying for the federal EITC (Form 511-EIC with a copy of the federal return), so the federal SSN requirement excludes ITIN-only filers.

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: Oklahoma 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.