California S Corporation Tax Deadlines 2026

When is the S Corporation tax filing deadline in California for 2026?

The California S Corporation tax return is due Mar 16, 2026 for the 2026 tax year. An extension is available until Sep 15, 2026.

Does California require S Corporation estimated tax payments?

Estimated payments are not typically required at the entity level for S Corporation in California, but confirm with California Franchise Tax Board.

What form do I file for a S Corporation in California?

S Corporation entities in California file using Form Form 100S. You can download the form from California Franchise Tax Board at https://www.ftb.ca.gov.

Can I get an extension for my California S Corporation tax return?

Yes. California allows an extension for S Corporation returns until Sep 15, 2026. Note that an extension gives you more time to file, not more time to pay — any tax owed is still due by the original deadline of Mar 16, 2026.

What are the penalties for filing late in California?

California typically charges a failure-to-file penalty (usually 5% of unpaid tax per month, up to 25%) and a failure-to-pay penalty (usually 0.5-1% per month). Interest also accrues on unpaid balances. Filing for an extension by the original deadline avoids the failure-to-file penalty but not the failure-to-pay penalty.

Where can I file California S Corporation taxes?

File through California Franchise Tax Board. Visit https://www.ftb.ca.gov for e-filing options, downloadable forms, and payment portals.