Buying a second-hand house means that buyers and sellers sign relevant sales contracts and determine the down payment and loan amount. The intermediary will take the buyer and the seller to the guarantee company or the bank to sign a loan contract, submit relevant information and wait for the bank to approve the loan. After the loan is approved, it can be transferred. After the transfer is completed, the buyer holds the real estate license to the Housing Authority for mortgage. After the mortgage is completed, the bank will lend to the seller. Therefore, second-hand housing transactions must not forget to apply for a mortgage. Without mortgage, the seller can't get the final payment, and there are no restrictions on the property.