California Elections Code Section 3109

If any special absentee voter returns to the county of his or her residence after the final day for making application for a vote by mail ballot, he or she may appear before the elections official and make application for registration, vote by mail ballot, or both. The elections official shall register the voter, if he or she is not registered, and deliver to him or her a vote by mail ballot which may be voted in the elections official`s office or voted outside the elections official`s office on or before the close of the polls on the day of election and returned as are other vote by mail ballots.