How do I file an extension for a California S-Corp (Form 3539)?

Download the most up to date form and instructions from https://ftb.ca.gov

2015 Instructions for Form FTB 3539
Use form FTB 3539, Payment for Automatic Extension for Corporations and
Exempt Organizations, only if both of the following apply:
• The corporation or exempt organization cannot file its 2015 California (CA) tax
return by the original due date.
• The corporation or exempt organization owes tax for the 2015 taxable year.

According to the current instructions, Form 3539 only needs to be filed if taxes are due. Well that's certainly a good idea. Dear IRS, give California a call.

For S-Corps, with a fiscal year from January 1st to the end of December, the extension for filing form 100S is extended to October 15th, 2014.