In general, the date of filing an instrument under the General Corporation Law is the date on which it is received by the Secretary of State's office. Cal. Corp. Code §110(a). There are at least three exceptions to this rule.
Annual Statements of Information
First, the statute excludes statements of information filed pursuant to Section 1502 (oddly, the additional statement required to be filed by publicly traded corporations is not excepted).
The second exception is when in the judgment of the Secretary of State a filing is intended to be coordinated with the filing of another corporate document that cannot be filed.
Future Filings and Future Effective Dates
The third exception comes into play when a filer requests that the instrument be filed at a future time. Cal. Corp. Code § 110(c). In that case, the Secretary of State must file the document on the requested date that is not more than 90 days after receipt, including a Saturday, Sunday or legal holiday, if the document is received by the Secretary of State at least one business day prior to the requested filing date. Requesting a future filing date is not the same as a future effective date. Section 110(c) provides that any instrument may provide that it is to become effective not more than 90 days subsequent to its filing date. This allows for the instrument to be filed but not yet effective. If there is a change in heart, the instrument can be prevented from becoming effective by filing a certificate stating that the instrument has been revoked by "appropriate corporate action" and is null and void. The certificate must be executed in the same manner as the original instrument and filed before the effective date. If the instrument is a merger agreement, the certificate revoking the earlier filing need only be executed on behalf of one of the constituent corporations. If no revoking certificate is filed, the instrument becomes effective on the date specified.