The mortgage interest rate is the benchmark interest rate plus the floating ratio. If the benchmark interest rate is 4.9% and floating 10%, the mortgage interest rate is 4.9 %× (1+10%) = 5.39%. After the loan, the floating ratio will not affect the borrowed house payment, but the benchmark interest rate will. The benchmark interest rate will change at any time, but the interest rate increase or discount will always follow the loan until it is repaid.