Cal. Rev. & Tax. Code § 8105

All applications for refund provided under this article shall be filed within three years from the date of the purchase of the motor vehicle fuel or, if the tax was not invoiced at the time of the purchase of the motor vehicle fuel, the application for refund shall be filed within six months after the receipt of an invoice for the tax, whichever period expires later. Any application filed after the time prescribed shall not be considered for any purpose by the Controller, the Treasurer, or the state.