California Code, Revenue and Taxation Code - RTC § 51.5

(a) Notwithstanding any other provision of the law, any error or omission in the determination of a base year value pursuant to paragraph (2) of subdivision (a) of Section 110.1, including the failure to establish that base year value, which does not involve the exercise of an assessor's judgment as to value, shall be corrected in any assessment year in which the error or omission is discovered.

(b) An error or an omission described in subdivision (a) which involves the exercise of an assessor's judgment as to value may be corrected only if it is placed on the current roll or roll being prepared, or is otherwise corrected, within four years after July 1 of the assessment year for which the base year value was first established.

(c) An error or an omission involving the exercise of an assessor's judgment as to value shall not include errors or omissions resulting from the taxpayer's fraud, concealment, misrepresentation, or failure to comply with any provision of law for furnishing information required by Sections 441, 470, 480, 480.1, and 480.2, or from clerical errors.

(d) If a correction authorized by subdivision (a) or (b) reduces the base year value, appropriate cancellations or refunds of tax shall be granted in accordance with this division. If the correction increases the base year value, appropriate escape assessments shall be imposed in accordance with this division.

(e) The existence of a clerical error shall be proved by a preponderance of the evidence, except that if the correction is made more than four years after July 1 of the assessment year for which the base year value was first established the clerical error shall be proved by clear and convincing evidence, including the papers in the assessor's office. Nothing in this subdivision shall be construed to change the standard of proof applicable to a determination of the value of property.

(f) For purposes of this section: