Cal. Elec. Code § 3107

If any special absentee voter is released from service after the closing date of registration for an election and has returned to the county of his or her residence and is not a registered voter, he or she may apply in person to the elections official for permission to register. If the elector furnishes documentary proof of release from service after the closing date of registration for the election, the elections official shall allow him or her to be registered and to vote in the election. On or before the day of election the elections official shall deliver to the precinct board a list of special absentee voters registered under this section.