How Amortization Schedule Works

Amortization schedule is a repayment plan that outlines the loan amount, interest rate, and loan term, and calculates the monthly payment required to pay off the loan.

The Mechanism

The core cause-and-effect chain of an amortization schedule is the calculation of the monthly payment based on the loan amount, interest rate, and loan term, resulting in a schedule of payments that gradually reduce the outstanding balance. This process involves the application of compound interest to the outstanding balance, which in turn determines the interest portion of each monthly payment.

Step-by-Step

1. The lender calculates the monthly payment by dividing the loan amount by the number of payments, which is typically 360 months for a 30-year mortgage, and then adjusting for the interest rate, resulting in a monthly payment of approximately $1,073 for a $200,000 loan at 4% interest.
2. The borrower makes the monthly payment, which is then split into the interest portion and the principal portion, with the interest portion being calculated as the outstanding balance multiplied by the monthly interest rate, resulting in an interest portion of $665 for the first payment.
3. The interest portion is deducted from the monthly payment, leaving the principal portion, which is then subtracted from the outstanding balance, resulting in a reduction of the outstanding balance by $408 for the first payment.
4. The lender updates the amortization schedule to reflect the new outstanding balance, which is then used to calculate the interest portion of the next monthly payment, resulting in a decrease in the interest portion of $2.73 for the second payment.
5. The process is repeated for each monthly payment, with the interest portion decreasing and the principal portion increasing over time, resulting in the loan amount being paid off in full after 360 months, with a total interest paid of $143,739.
6. The final monthly payment is made, and the loan is considered paid in full, with the borrower having paid a total of $343,739, including $143,739 in interest, over the 30-year loan term.

Key Components

• Loan amount: the initial amount borrowed, which determines the monthly payment and the total interest paid.
• Interest rate: the rate at which interest is charged on the outstanding balance, which affects the monthly payment and the total interest paid.
• Loan term: the length of time over which the loan is repaid, which determines the number of payments and the monthly payment.
• Amortization schedule: the table or chart that outlines the monthly payments, interest portions, and principal portions, and tracks the outstanding balance over time.

Common Questions

What happens if the borrower misses a payment? If the borrower misses a payment, the outstanding balance will increase, resulting in a higher interest portion for the next payment, and potentially leading to late fees and penalties.

How does the interest rate affect the monthly payment? A higher interest rate will result in a higher monthly payment, as more of the payment will go towards interest, such as a $200,000 loan at 6% interest, which would have a monthly payment of $1,194.

What is the difference between the interest portion and the principal portion? The interest portion is the amount of the monthly payment that goes towards paying interest on the outstanding balance, while the principal portion is the amount that goes towards reducing the outstanding balance, such as the first payment on a $200,000 loan at 4% interest, which would have an interest portion of $665 and a principal portion of $408.