Because the decline in house prices has nothing to do with the monthly payment, it needs to be repaid according to the original monthly payment. The monthly payment will not change when the house price falls, because the house price decline has nothing to do with the repayment and interest payment of the mortgage loan. When buying a house, the mortgage loan contract signed with the bank has clearly defined the amount of bank loans, and the loan contract also clearly States the amount of monthly repayment of principal. The monthly payment has nothing to do with the rise and fall of house prices, but with the loan interest rate.