Cal. RTC § 11317

(a) An escape assessment shall be entered on the current private railroad car tax record, and if this is not the record for the year in which the property escaped assessment, the entry shall be followed with “escape assessment for year 20__.” The property shall be assessed at the same value and taxed at the same rate as it would have been assessed and taxed had it not escaped.

(b) If the assessments are made as a result of an audit that discloses that property assessed to the party audited has been incorrectly assessed for a past tax year for which taxes have been paid and a claim for refund is not barred by Section 11553, the tax refunds, including applicable interest under Section 11555, resulting from the incorrect assessments shall be an offset against proposed tax liabilities, including accumulated penalties and interest, resulting from escaped assessments for any tax year covered by the audit. If the refunds exceed any proposed tax liabilities, including penalties and interest, the excess shall be processed in accordance with Section 11551.

(c) Beginning with the 1981–82 fiscal year, assessments for the current year and escape assessments for prior years shall be entered using a 100-percent assessment ratio and the tax rates for years prior to the 1981–82 fiscal year shall be divided by four.