Cal. Civil Code § 1102.5

(a) If information disclosed in accordance with this article is subsequently rendered inaccurate as a result of any act, occurrence, or agreement subsequent to the delivery of the required disclosures, any inaccuracy resulting therefrom does not constitute a violation of this article. If at the time the disclosures are required to be made, an item of information required to be disclosed is unknown or not available to the seller, and the seller or the seller’s agent has made a reasonable effort to ascertain it, the seller may use an approximation of the information, provided the approximation is clearly identified as such, is reasonable, is based on the best information reasonably available to the seller or the seller’s agent, and is not used for the purpose of circumventing or evading this article. (b) The requirements of this article in effect on the date that all of the parties enter into a contract or agreement subject to this article are the requirements that shall apply to that contract or agreement. An amendment to this article that becomes effective after that date does not alter the requirements under this article that shall apply to that contract or agreement, unless the applicable statute provides otherwise.