A Residential Cooperative Unit Affidavit is a legal document used by cooperative housing societies to attest to the fact that a unit is owned by a particular individual or family. It is typically used to transfer ownership of a unit or to obtain financing for a unit. There are two different types of Residential Cooperative Unit Affidavits: a Seller's Affidavit and a Buyer's Affidavit. The Seller's Affidavit is used to transfer ownership of a unit from the seller to the buyer, while the Buyer's Affidavit is used to demonstrate to a lender that the buyer has an ownership interest in the unit. Both affidavits must be signed by the cooperative housing society's board of directors and the purchaser in order to be considered valid.