Oklahoma Business Tax Deadlines (2026)

Next Deadline: May 15 — Form 990 due for nonprofits

Federal Tax Deadlines (2026)

Oklahoma State Tax Deadlines (2026)

Quarterly Estimated Tax Deadlines in Oklahoma

Oklahoma follows the federal estimated tax schedule:

Estimated payments are required if you expect to owe $1,000 or more in Oklahoma income tax after withholding and credits.

Oklahoma-Specific Tax Requirements

Oklahoma imposes a graduated individual income tax with rates ranging from 0.25% to 4.75% (the top rate applies to income over $7,200 for single filers / $12,200 for joint filers). Business income from sole proprietorships and pass-through entities flows through to the individual return. Oklahoma is notable for having relatively low top rates compared to coastal states.

The Corporate Income Tax rate is a flat 4% on net income apportioned to Oklahoma. Additionally, Oklahoma imposes an annual Franchise Tax of $1.25 per $1,000 of capital allocated or employed in Oklahoma, with a minimum of $25 and a maximum of $20,000. The franchise tax return is due July 1 each year, separate from the income tax return.

Oklahoma's Sales and Use Tax has a state rate of 4.5%, with city and county additions that can push combined rates as high as 11.5% in some jurisdictions — among the highest combined rates in the nation. Monthly filers must remit by the 20th of the following month. Employers are required to withhold Oklahoma income tax from employee wages. The state does not impose a personal property tax at the state level, but counties may assess personal property used in business.

What Happens If You Miss an Oklahoma Tax Deadline?

Oklahoma's late filing penalty is 5% per month of the unpaid tax, up to a maximum of 25%. A late payment penalty of 5% of the unpaid tax is added as a one-time charge if the tax is not paid by the due date. If both apply, the combined penalties can reach 30%.

Interest on unpaid taxes accrues at 1.25% per month (15% per year) from the original due date. For estimated tax underpayments, a penalty of 20% of the underpaid amount may apply.

Oklahoma grants a 6-month extension for individual and corporate income tax returns if you file the extension request by the original due date. However, you must pay at least 90% of the total tax liability with the extension request. Franchise tax returns generally cannot be extended, and the July 1 deadline is firm. Failure to pay franchise tax can result in suspension of your corporate charter.

Oklahoma Tax Commission

Website: https://oklahoma.gov/tax.html

Phone: (405) 521-3160

Online Filing: https://oktap.tax.ok.gov/

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