In the process of buying and selling second-hand houses, it usually takes 1 to 3 months from the signing of the sales contract between the buyer and the seller to the completion of the real estate transaction. There is a problem of "payment first or transfer first" in real estate transactions. If there are no regulatory measures for trading funds, unnecessary disputes will easily occur. Only by means of fund supervision and fund custody can the security of second-hand housing transaction funds be truly guaranteed. In these two modes, the funds are frozen through the special account of the bank, and no one else can use the funds without the agreed authorization of the buyer and the seller. In addition, other housing payment delivery modes will also make the transfer of funds have certain risks. Fund supervision is only a kind of guarantee behavior in the process of buying and selling second-hand houses, which is not mandatory and does not affect the transaction process. Generally, some houses originally had loans, and the next family paid the down payment to the last family to cancel the mortgage (that is, they went to the bank to pay off the loan and went to the trading center to apply for cancellation of the mortgage record information), but the last family used the money for other purposes, and the premise of house transfer was that the house had to be mortgaged and cancelled, which made it impossible to transfer the house (because there was no cancellation of the mortgage). Fund supervision is to keep the house payment paid by the purchaser in the third-party fund account agreed by the upper and lower households for special purposes. In other words, it can only be used to pay off the last loan to ensure the smooth and safe trading process. For general fund supervision accounts, intermediaries will provide their special accounts. If you don't go through an intermediary or don't trust an intermediary, you can also designate a bank or directly entrust a real estate trading center, and all of them have relevant supervision accounts. Finally, it is necessary to stipulate the account name, account number, when and how to lend money in the contract. (For example, with the consent of the next lender, the fund supervision account will directly transfer the money to the original lender to pay off the last loan on the repayment date agreed by the last lender) and so on.