California Business Tax Extension 2026: 2025 Tax-Year Filing Guide
LLC & Partnership · S Corporation · C Corporation · Fiduciary
This guide explains how to file a California (CA) business tax extension for each entity type. California extensions vary by entity, and filing extensions generally do not extend the time to pay. Confirm the applicable FTB payment form and deadline. 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 CA return.
Remember, payment is still due by the original deadline. In other words, extensions only extend filing time.
California (CA) 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.
California LLC Tax Extension: Filing Details
A calendar-year partnership or LLC taxed as a partnership generally files Forms 565 and 568, as applicable, when a California filing obligation applies. For the 2025 calendar-year return, the extended filing deadline is October 15, 2026.
In addition, the extension applies to filing time only. Therefore, pay required California tax by the original deadline to limit penalties and interest.
The extension applies to filing time only. Pay required California tax by the original deadline to limit penalties and interest.
California S Corporation Tax Extension: Filing Details
For an S corporation, a calendar-year business generally files Form 100S, as applicable, when a California filing obligation applies. For the 2025 calendar-year return, the extended filing deadline is September 15, 2026.
California C Corporation Tax Extension: Filing Details
For a C corporation, a calendar-year business generally files Forms Form 100 and Form 100W, as applicable, when a California filing obligation applies. For the 2025 calendar-year return, the extended filing deadline is November 16, 2026.
The extension applies to filing time only. Pay required California tax by the original deadline to limit penalties and interest.
The extension applies to filing time only. Pay required California 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 541, as applicable, when a California filing obligation applies. 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 California business tax extensions.
| Entity Type | CA Return Form | Extension Method | Extended Deadline |
|---|---|---|---|
| LLC / Partnership | Form 565 or Form 568 | Automatic 7-month extension; FTB 3537 or FTB 3538 | Oct. 15, 2026 |
| S Corporation | Form 100S | FTB 3539 | Sept. 15, 2026 |
| C Corporation | Form 100 / Form 100W | FTB 3539 | Nov. 16, 2026 |
| Fiduciary / Estate / Trust | Form 541 | FTB fiduciary extension instructions | Oct. 15, 2026 |
Frequently Asked Questions
Quick answers about California business tax extensions – but always confirm the current rules with the California Franchise Tax Board.
Visit California Franchise Tax BoardYes. However, the applicable entity-specific requirements listed above must be satisfied. California 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. For federal filing guidance, see our IRS Form 7004 guide. If you need an individual rather than business extension, see our California individual tax extension page.
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, non-corporate business entities generally receive a seven-month extension, S corporations receive six months, C corporations receive seven months, and fiduciaries receive six months.
Review the California Franchise Tax Board guidance for the entity’s return. Additionally, the FTB publishes the most current forms (FTB 3537, FTB 3538, FTB 3539, Form 541) and any changes to extension periods or payment thresholds.
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