Legal analysis: five mortgages, one for the customer, one for the company, one for the real estate bureau, one for the bank and one for the deed tax. There are four customers in installments, one for personal use, one for filing by the company, one for filing by the real estate bureau, and one for filing when the deed tax is paid, and a formal house purchase contract is signed. At the proposed time and place, the buyer prepares all the vouchers and formally signs the purchase contract with the developer or agent. The difference between pre-sale contract (auction house) and sales contract (existing house): The purchase contract generally includes two types: the pre-sale contract of commercial housing (auction house) and the sales contract of commercial housing (existing house).

Legal basis: Article 3 1 1 of the Civil Code of People's Republic of China (PRC) * * * If the disposer has no right to transfer the real estate or chattel to the assignee, the owner has the right to take it back; Unless otherwise provided by law, the transferee shall acquire the ownership of the real estate or chattel under any of the following circumstances: (1) the transferee acquires the real estate or chattel in good faith; (2) Transfer at a reasonable price; (3) The transferred immovable property or movable property that should be registered according to law has been registered, and the transferred immovable property or movable property that does not need to be registered has been delivered to the transferee. If the transferee obtains the ownership of real estate or movable property in accordance with the provisions of the preceding paragraph, the original owner has the right to claim damages from the unauthorized person. Where the parties have acquired other real rights in good faith, the provisions of the preceding two paragraphs shall apply mutatis mutandis.