Missouri Business Tax Extension 2026: 2025 Tax-Year Filing Guide
LLC & Partnership · S Corporation · C Corporation · Fiduciary
This guide explains how to file a Missouri (MO) business tax extension for each entity type. For example, CBT taxpayers generally receive six months, while partnerships generally receive five months. However, estimated tax remains due by the original deadline.
Need a pro? Connect with a U.S.-based CPA or EA to prepare and file your MO return.
Remember, payment is still due by the original deadline. In other words, extensions only extend filing time.
Missouri (MO) 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.
Missouri LLC Tax Extension: Filing Details
A calendar-year partnership or LLC taxed as a partnership generally files Forms State business return and State business return, as applicable, when a Missouri filing obligation applies. For the 2025 calendar-year return, the extended filing deadline is September 15, 2026.
In addition, the extension applies to filing time only. Therefore, pay required Missouri tax by the original deadline to limit penalties and interest.
The extension applies to filing time only. Pay required Missouri tax by the original deadline to limit penalties and interest.
Missouri S Corporation Tax Extension: Filing Details
For an S corporation, a calendar-year business generally files Form State business return when it has a Missouri filing obligation. For the 2025 calendar-year return, the extended filing deadline is October 15, 2026.
Missouri C Corporation Tax Extension: Filing Details
For a C corporation, a calendar-year business generally files Form State business return or State business return and must follow Missouri corporate-income-tax extension rules. For the 2025 calendar-year return, the extended filing deadline is October 15, 2026.
The extension applies to filing time only. Pay required Missouri tax by the original deadline to limit penalties and interest.
The extension applies to filing time only. Pay required Missouri 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 State fiduciary return when it has a Missouri fiduciary filing obligation. For the 2025 calendar-year return, the extended filing deadline is October 15, 2026.
Quick Reference: Deadlines and Forms
The table below provides a quick reference to Missouri business tax extensions. See our IRS Form 7004 guide, Missouri individual tax extension, and business tax extension resource for related guidance.
| Entity Type | NJ Return Form | Extension Method | Extended Deadline |
|---|---|---|---|
| LLC / Partnership | State business return / State business return | Federal 5-month; State extension form / State extension form | Sept. 15, 2026 |
| S Corporation | State business return | State extension form | Oct. 15, 2026 |
| C Corporation | State business return / State business return | State extension form | Oct. 15, 2026 |
| Fiduciary / Estate / Trust | State fiduciary return | Form State fiduciary extension | Oct. 15, 2026 |
Frequently Asked Questions
Quick answers about Missouri business tax extensions – but always confirm the current rules with the Missouri Department of Revenue.
Visit MO DORYes. However, the applicable entity-specific requirements listed above must be satisfied. Missouri 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 Missouri Department of Revenue guidance for the entity’s return. Additionally, the DOR publishes the most current forms (State extension form, State extension form, State fiduciary extension, etc.) and any changes to extension periods or payment thresholds.
Estimated reading time: 6 minutes