Normal mortgage expenses cannot exceed 50% of the family's income and expenditure. That is to say, before taking out a loan to buy a house, the borrower must consider the future repayment pressure. If the monthly repayment expenditure exceeds the household income and expenditure by more than 30% during the future mortgage period, then it is not suitable for a loan to buy a house. Considering that Chinese people are relatively frugal and love to save, it can be raised appropriately, but the monthly mortgage repayment cannot exceed 50% of income and expenditure.