California Code, Revenue and Taxation Code - RTC § 23331

(a) For the purposes of this article, the effective date of dissolution of a corporation is the date on which the certified copy of the court decree, judgment, or order declaring the corporation duly wound up and dissolved is filed in the office of the Secretary of State or the date on which the certificate of winding up, if necessary, and the certificate of dissolution are filed in the office of the Secretary of State.  For the purposes of this article, the effective date of withdrawal of a foreign corporation is the date on which the certificate of withdrawal is filed in the office of the Secretary of State.

(b) The Secretary of State shall, through an information program and by forms and instructions provided to taxpayers, recommend that all documents required by this article to be filed with the Secretary of State be sent, if mailed, by certified mail with return receipt requested.  The Secretary of State shall also provide the taxpayers a filing response within 21 days of receipt.