Problem description:

Explain the principle and calculate with examples.

Analysis:

Calculation formula of equal repayment

Monthly repayment amount = [principal * monthly interest rate * (1+ monthly interest rate) repayment months ]/[( 1+ monthly interest rate) repayment months-1]

In which: monthly interest = residual principal * monthly interest rate of loan.

Monthly principal = monthly contribution-monthly interest

Calculation principle: from the beginning of monthly contribution, the bank collects the interest of the remaining principal first, and then the principal; The proportion of interest in monthly payment decreases with the decrease of residual principal, and the proportion of principal in monthly payment increases, but the total monthly payment remains unchanged.

Calculation formula of monthly decreasing repayment amount

Monthly principal and interest repayment amount = (principal/repayment months)+(principal-accumulated repaid principal) * monthly interest rate.

Monthly principal = total principal/repayment months

Monthly interest = (principal-accumulated principal repayment) * monthly interest rate

Calculation principle: the amount of principal returned every month is always the same, and the interest decreases with the decrease of the remaining principal.

Friends who borrow money to buy a house should have this experience. After the People's Bank of China adjusted the interest rate (the annual interest rate was raised from 0.0504 to 0.053 1, and it took effect on June 65438+1 October 2005), everyone's monthly repayment amount increased a little. For example, I borrowed 220,000 yuan from China Construction Bank in early 2003. After 20 years, I still pay 1, 456.77 yuan every month. After adjustment, I paid RMB 65,438+0,489.85 per month from June 2005. After the interest rate adjustment, the bank's calculation method is to recalculate the whole repayment period (240 months) according to the new interest rate, so as to get the monthly repayment amount.

This practice is problematic, and it does not follow the principle of repayment calculation determined by banks: monthly interest = residual principal * monthly interest rate of loans. Starting from the monthly contribution, the bank collects the interest on the remaining principal first, and then the principal; The proportion of interest in monthly payment decreases with the decrease of residual principal, and the proportion of principal in monthly payment increases, but the total monthly payment remains unchanged.

Because the interest rate is high, the interest paid in advance will be more. According to the bank's algorithm, it is not determined that you have paid the corresponding principal.

The correct calculation method is: when the interest rate adjustment takes effect, calculate your remaining principal and the number of remaining repayment periods, so as to get your monthly repayment amount, instead of recalculating the whole repayment period at the new interest rate after the interest rate adjustment, because the adjusted interest rate cannot be used before the adjustment.

For me, the amount of 1489.85 has been paid for 20 years, and the overpayment is about 2000 yuan. You can also calculate GGJJDDMM carefully.

I put it in the financial forum because I want to pass on the expert's argument here. If I finally confirm this, I will complain to China Consumers Association.