Oklahoma Business Tax Extension 2026: 2025 Tax-Year Filing Guide
LLC & Partnership · S Corporation · C Corporation · Fiduciary
This guide explains how to file a Oklahoma (OK) business tax extension for each entity type. For example, Oklahoma taxpayers generally receive six months, while partnerships generally receive seven months. However, estimated tax remains due by the original deadline.
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Remember, payment is still due by the original deadline. In other words, extensions only extend filing time.
Oklahoma (OK) rules depend on entity type. Next, confirm the entity’s classification, file the required extension or retain federal proof when applicable, and pay required tax by the original deadline.
Oklahoma LLC Tax Extension: Filing Details
A calendar-year partnership or LLC taxed as a partnership generally files Forms Form 514, as applicable, when a Oklahoma filing obligation applies. For the 2025 calendar-year return, the extended filing deadline is December 15, 2026.
In addition, the extension applies to filing time only. Therefore, pay required Oklahoma tax by the original deadline to limit penalties and interest.
The extension applies to filing time only. Pay required Oklahoma tax by the original deadline to limit penalties and interest.
Oklahoma S Corporation Tax Extension: Filing Details
For an S corporation, a calendar-year business generally files Form Form 512-S when it has a Oklahoma filing obligation. For the 2025 calendar-year return, the extended filing deadline is December 15, 2026.
Oklahoma C Corporation Tax Extension: Filing Details
For a C corporation, a calendar-year business generally files Form Form 512 and must follow Oklahoma oklahoma tax extension rules. For the 2025 calendar-year return, the extended filing deadline is December 15, 2026.
The extension applies to filing time only. Pay required Oklahoma tax by the original deadline to limit penalties and interest.
The extension applies to filing time only. Pay required Oklahoma tax by the original deadline to limit penalties and interest.
Fiduciary, Estate, and Trust Filing Details
Finally, a calendar-year estate or trust generally files Form Form 513 when it has a Oklahoma fiduciary filing obligation. For the 2025 calendar-year return, the extended filing deadline is December 15, 2026.
Quick Reference: Deadlines and Forms
The table below provides a quick reference to Oklahoma business tax extensions. See our IRS Form 7004 guide, Oklahoma individual tax extension, and business tax extension resource for related guidance.
| Entity Type | OK Return Form | Extension Method | Extended Deadline |
|---|---|---|---|
| LLC / Partnership | Form 514 | Federal extension;; Form 504-C | Oct. 15, 2026 |
| S Corporation | Form 512-S | Form 504-C | Dec. 15, 2026 |
| C Corporation | Form 512 | Form 504-C | Dec. 15, 2026 |
| Fiduciary / Estate / Trust | Form 513 | Form Form 504-C | Dec. 15, 2026 |
Frequently Asked Questions
Quick answers about Oklahoma business tax extensions – but always confirm the current rules with the Oklahoma Division of Taxation.
Visit OK DORYes. However, the applicable entity-specific requirements listed above must be satisfied. Oklahoma grants extensions to LLCs, partnerships, S corporations, C corporations, and fiduciaries, but the rules – including which form to file, how long the extension lasts, and the payment threshold – vary by entity type.
Generally no. In other words, pay required tax by the original deadline and confirm the current state payment rules. An extension of time to file does not extend the time to pay – failing to pay by the original deadline can result in penalties and interest, even if the return is filed within the extended window.
No. In practice, partnerships, S corporations, C corporations, and fiduciaries can use different original dates, extension periods, or forms. For 2025 calendar-year returns filed in 2026, partnerships and LLCs taxed as partnerships get a five-month extension (Sept. 15), while the others generally get a six-month extension (Oct. 15).
Review the Oklahoma Division of Taxation guidance for the entity’s return. Additionally, the DOR publishes the most current forms (Form 504-C, Form 504-C, Form 504-C, etc.) and any changes to extension periods or payment thresholds.
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