Cal. Rev. & Tax. Code § 616
On or before July 1, annually, the assessor shall complete the local roll. He shall make and subscribe an affidavit on the roll substantially as follows:
"I, ____, Assessor of ____ County, swear that between the lien date and July 1, 19____, I have made diligent inquiry and examination to ascertain all the property within the county subject to assessment by me, and that it has been assessed on the roll, according to the best of my judgment, information, and belief, at its value as required by law; and that I have faithfully complied with all the duties imposed on the assessor under the revenue laws; and that I have not imposed any unjust or double assessment through malice, ill will, or otherwise; nor allowed anyone to escape a just and equal assessment through favor, reward, or otherwise."
The failure to make or subscribe this affidavit, or any affidavit, does not affect the validity of the assessment.
The assessor may require from any of his deputies an affidavit on the roll similar to his own.
Ca. Rev. and Tax. Code § 616