"California property tax law requires the Assessor to revalue real property at the time the ownership of the property changes. Because of this law, you may receive one or two supplemental tax bills, depending on when your loan closes.
The supplemental tax bills are not mailed to your lender. If you have arranged for your property tax payments to be paid through an impound account, the supplemental tax bills will not be paid by your lender. It is your responsibility to pay these supplemental bills directly to the tax collector. If you have any question concerning this matter, please call your local tax collector's office."
Ca. Civ. Code § 1102.6c