Legal analysis: Under normal circumstances, when buying a house, you should sign a contract and issue a down payment property invoice. After signing the mortgage purchase contract, the bank can ask the developer for the purchase contract after successfully issuing the loan. After paying the down payment, the average time to get the purchase contract is less than one month, and the specific time of each sales office is similar. After the loan comes down, you can sign the contract and then invoice the purchase contract; As long as the Housing Authority does not record the purchase, it can sign the contract at any time; Legal basis: Article 12 of People's Republic of China (PRC) Contract Law, the contents of the contract are agreed by the parties, and generally include the following clauses: (1) the name and address of the parties; (2) Subject matter; (3) quantity; (4) quality; (6) Time limit, place and method of performance; (7) Liability for breach of contract; (8) dispute resolution methods. The parties may conclude a contract by referring to the model texts of various contracts.

Legal basis: Article 16 of the Measures for the Administration of Commercial Housing Sales. When a real estate development enterprise sells commercial housing, it shall conclude a written contract for the sale of commercial housing with the buyer. Commercial housing sales contracts shall contain the following main contents:

(1) The name and domicile of the party concerned;

(2) Basic information of commercial housing;

(three) the way of commercial housing sales;

(four) the method of determining the price and total price of commercial housing, the method of payment and the time of payment;

(5) Terms and date of delivery;

(six) decoration, equipment standards commitment;

(seven) water supply, power supply, heating, gas, communications, roads, greening and other supporting infrastructure and public facilities delivery commitments and related rights and responsibilities;

(eight) the ownership of public supporting buildings;

(nine) the way to deal with the area difference;

(10) Handling matters related to the registration of property rights;

(eleven) the method of dispute resolution;

(12) Liability for breach of contract;

(13) Other matters agreed by both parties.