California Code, Revenue and Taxation Code - RTC § 20824

If the deferment claim is filed timely, then any delinquent penalties and interest for that fiscal year shall be canceled unless the failure to perfect the claim was due to willful neglect on the part of the claimant or his or her representative. In the event of such willful neglect, any property tax deferment subvention payment may be used only if it is accompanied by sufficient amounts to pay the delinquent interest and penalties.