California Code, Revenue and Taxation Code - RTC § 18604

(a) The Franchise Tax Board may grant a reasonable extension of time for filing any return, declaration, statement, or other document required by Part 11 (commencing with Section 23001), in the manner and form as the Franchise Tax Board may determine.  No extension or extensions shall aggregate more than seven months from the due date for filing the return.

(b) An extension of time granted pursuant to this section is not an extension of time for payment of tax required to be paid on or before the due date of the return without regard to extension.  Underpayment of tax penalties shall be imposed as provided by law without regard to any extension granted under this section.