California Code, Revenue and Taxation Code - RTC § 402.5

When valuing property by comparison with sales of other properties, in order to be considered comparable, the sales shall be sufficiently near in time to the valuation date, and the properties sold shall be located sufficiently near the property being valued, and shall be sufficiently alike in respect to character, size, situation, usability, zoning, or other legal restriction as to use unless rebutted pursuant to Section 402.1, to make it clear that the properties sold and the properties being valued are comparable in value and that the cash equivalent price realized for the properties sold may fairly be considered as shedding light on the value of the property being valued. “Near in time to the valuation date” does not include any sale more than 90 days after the valuation date.