The Seller and his Agent have to disclose many things about the property for sale.
We include a list of the disclosures required in California on our website to help you with that part of the legalize in the purchase of Real Estate.
If even just one single disclosure is not made to the buyer, the buyer has the right to terminate the transfer of Real Estate property. Further, whenever a new disclosure is made, the buyer has three (3) days the consider the disclosure and withdraw his offer on the property.
All disclosures are expected to be made before the transfer of property is signed by both parties.
Note that to make it easy there is a form one can use to make nearly all the disclosures at once: The Transfer Disclosure Statement. Also, the title company used in the transaction knows of which documents to use.
Note that there are cases when disclosures are not required.
Source: CAL. CIV. § 1102.3