Immediately upon the close of polls on election day, the county elections officials and the Secretary of State begin what is called the "semifinal official canvass of the vote" - the tallying of early-returned vote-by-mail ballots and the ballots cast in each of the state's 24,000+ voting precincts. The semifinal official canvass begins at 8:00 p.m. on election night and continues uninterrupted until the last precinct is counted and reported to the Secretary of State.
The vote tallying process actually begins before election night, with the vote-by-mail ballots. Counties may begin processing vote-by-mail seven (7) business days before the election. Having verified the signatures on the return envelopes, elections officials remove the voted ballots and process them through their vote tallying system. Under no circumstances may they tabulate the results until after the close of polls on election day. Most counties continue this processing until they begin their election-day preparations for counting the precinct votes. Mail ballots not counted by that time and all those received on election day, either through the mail or at the precincts, are tabulated during the official canvass of the vote.
The California Elections Code requires that the official canvass begin no later than the Thursday following the election, that it be open to the public, and that it continue daily (Saturdays, Sundays, and holidays excepted) for not less than six hours each day until completed. The county elections officials must complete the official canvass no later than the 28th day after the election and submit a certified statement of the results of the election to the Secretary of State by the 31st day.
By law, the activities undertaken during the official canvass include:
No later than the 38th day after the election, the Secretary of State must determine the votes cast for candidates for state and federal office and for the statewide ballot measures, certify those results, and issue certificates of nomination/election to those candidates who were nominated/elected.