Oklahoma Personal Tax Extension Guide

Form 504-I  ·  Individual Income Tax  ·  Personal Filing Guide

Oklahoma provides an automatic six-month extension for filing personal income tax returns to taxpayers who have received a federal extension and owe no Oklahoma income tax. If both conditions are met, the filing deadline moves from April 15, 2026, to October 15, 2026—no separate Oklahoma form required.

If you owe Oklahoma income tax, the automatic extension alone does not apply. You must file Form 504-I (Application for Extension of Time to File an Oklahoma Income Tax Return for Individuals) and submit payment of your Oklahoma tax liability by April 15, 2026. Attaching a copy of your federal extension to your Oklahoma return when filed is also required.

• Online (OkTAP): Pay by credit card, EFT, or e-check at oktap.tax.ok.gov. All payment types accepted through the Oklahoma Taxpayer Access Point.
• Mail: Use Form 504-I and mail to: Oklahoma Tax Commission, P.O. Box 26890, Oklahoma City, OK 73126-0890.

Oklahoma imposes a failure-to-file penalty of 25% of unpaid tax—one of the steepest flat filing penalties in the country. The failure-to-pay penalty is 5% of unpaid tax. These high penalties make it especially important to file Form 504-I and pay any balance by April 15 if you owe Oklahoma tax.

• If you owe Oklahoma tax, file Form 504-I and pay in full by April 15, 2026—the automatic extension does not apply when taxes are due.
• Attach a copy of your federal extension to your Oklahoma return when you file by October 15.
• Use OkTAP at oktap.tax.ok.gov for online payments.
• Oklahoma's 25% failure-to-file penalty is among the highest in the U.S.—do not miss the filing deadline.

Oklahoma's extension is automatic for taxpayers with a federal extension and no state tax due—but if you owe, act by April 15 with Form 504-I and full payment. File your return by October 15, 2026.

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