One extra payment cuts years off your loan and saves tens of thousands in interest
A single extra mortgage payment in a year typically shortens your loan by 4 to 5 months and saves between $10,000 and $30,000 in total interest, depending on your loan size, interest rate, and where you are in the repayment timeline. The exact number depends on three things: how much you owe right now, what your interest rate is, and how many years into the loan you are when you make the payment.
The reason the savings vary so much is that interest works backward from where you stand. If you make an extra payment early in a 30-year mortgage, you stop paying interest on that principal for 25+ years. If you make it in year 25, you stop paying interest for only 5 years. The earlier you pay extra, the more interest you prevent from accumulating.
The math is straightforward enough to work out yourself. Take your remaining loan balance, multiply it by your interest rate, divide by 12, and that is roughly how much interest you pay each month. An extra payment removes that monthly interest charge for every remaining month of the loan. But because your regular payments also chip away at principal, the actual savings compound—each extra payment means slightly less interest on the next payment, and so on.
Key Takeaways
- One extra payment made early in a 30-year mortgage typically saves $15,000 to $30,000 in interest and shortens the loan by roughly 4 to 5 months.
- The savings depend entirely on your remaining balance, your interest rate, and how many years are left—a payment in year 5 saves far more than a payment in year 25.
- A $300,000 loan at 6% interest costs roughly $1,500 per month in interest alone; an extra payment stops that charge from running for every remaining month.
- Making one extra payment per year is mathematically equivalent to paying an extra $100 to $150 per month, depending on your loan size.
How the savings change depending on where you are in the loan
The timing of your extra payment matters more than the payment itself. If you have a $300,000 mortgage at 6% interest with 25 years remaining, one extra payment saves roughly $25,000 in interest. If you make that same payment with only 5 years left, it saves roughly $4,000. The difference is the number of months that extra principal sits in your account, preventing interest from accruing.
Early in the loan, most of your regular payment goes to interest. On a $300,000 mortgage at 6%, your first payment might be $1,799, of which $1,500 goes to interest and only $299 to principal. An extra payment at that stage removes $1,500 in monthly interest charges for the remaining life of the loan. Later, when you are in year 20, your payment might be $1,799 but only $300 goes to interest and $1,499 to principal. An extra payment then removes only $300 per month in interest charges, because there are fewer months left.
This is why financial advisors often recommend making extra payments early rather than waiting. The compounding effect of preventing interest is strongest when you have the most time left.
Comparing one extra payment to other payoff strategies
One extra payment per year is not the only way to shorten a mortgage. You could instead pay an extra $100 to $150 per month, which spreads the same total amount across 12 months. You could make biweekly payments instead of monthly, which results in 26 half-payments per year (equivalent to 13 full payments). You could refinance to a shorter term, like 15 years instead of 30. Each approach saves interest, but they work differently.
An extra annual payment is simpler to manage if you receive a bonus or tax refund once a year. Biweekly payments require changing your payment schedule with your lender and may not be available on all loans. Refinancing locks in a new rate and resets the clock, which only makes sense if rates have dropped or you plan to stay in the home long enough to recoup closing costs.
| Strategy | How it works | Best for |
|---|---|---|
| One extra payment per year | Pay one full monthly payment as a lump sum once yearly | People with annual bonuses or tax refunds |
| Extra $100–$150 monthly | Add a fixed amount to your regular payment every month | People with consistent monthly cash flow |
| Biweekly payments | Pay half your monthly payment every two weeks (26 payments = 13 months) | People paid biweekly who want automatic acceleration |
| Refinance to 15 years | Take out a new loan at a new rate and term | People with lower rates available and stable income |
The savings from all these methods are similar in magnitude—they all shorten the loan by several years and save tens of thousands in interest. The difference is which one fits your cash flow and your lender's rules.
What happens to your monthly payment when you pay extra
Making one extra payment does not change your regular monthly payment. Your lender still expects the same amount each month. The extra payment is separate—you send it in addition to your regular payment, usually with a note specifying that it should go toward principal.
Some lenders allow you to specify this in your online account. Others require you to send a check or call to instruct them. A few older loan documents may not allow extra payments without penalty, though this is rare on mortgages issued in the last 20 years. Before making an extra payment, check your loan documents or call your lender to confirm there is no prepayment penalty and to ask how to may support the payment is credited to principal rather than held as a credit toward future payments.
If you pay extra and your lender applies it to next month's payment instead of principal, you have not shortened the loan—you have just prepaid. This is why the instruction matters. A single phone call to your lender clarifies the process and ensures your money does what you intend.
Real numbers: what $300,000 at 6% actually saves
A concrete example shows how the math works. Assume a $300,000 mortgage at 6% interest, 30-year term, with a monthly payment of $1,799. Over 30 years, you pay roughly $647,000 in total (principal plus interest). The interest alone is about $347,000.
If you make one extra $1,799 payment in year 1, you reduce the remaining balance by that amount when ready. That $1,799 no longer accrues interest for the next 29 years. At 6% annual interest, that is roughly $1,500 per month in interest prevented. Over 29 years, that single payment saves approximately $25,000 to $28,000 in interest and shortens the loan by about 4 to 5 months.
If you make that same extra payment in year 15 instead, the remaining balance is lower, so the interest rate applies to less principal. The savings drop to roughly $10,000 to $12,000, and the loan shortens by about 1 to 2 months. The difference between year 1 and year 15 is the number of years the extra principal has to prevent interest from running.
These numbers vary by lender, by exact rate, and by how your loan amortizes, but they illustrate the principle: earlier payments save more, and the savings are substantial enough to matter.
When an extra payment might not be the best move
An extra mortgage payment saves interest, but it is not always the smartest use of money. If you carry credit card debt at 18% interest, paying down the card first saves more money per dollar than paying down a mortgage at 6%. If you have no emergency fund, an extra mortgage payment leaves you vulnerable to unexpected costs. If your mortgage rate is very low—below 3%—and you could earn 4% or 5% in a savings account, the math shifts.
Similarly, if you are in the last few years of a 30-year mortgage, the interest savings from one extra payment are modest. You might accomplish more by investing that money or paying down other debt. The decision depends on your full financial picture, not just the mortgage math.
How to instruct your lender to explore the extra payment correctly
When you send an extra payment, include a written note or use your lender's online system to specify that it should be applied to principal, not to next month's regular payment. Some lenders have a specific field in their payment portal for this. Others require a letter or a phone call.
The safest approach is to call your lender before sending the payment and ask: "I want to make an extra payment toward principal. How should I send it, and how do I may support it is credited correctly?" Write down the name of the person you spoke with and the date. Then send the payment as instructed and keep the confirmation. A few weeks later, log into your account and verify that your principal balance dropped by the amount you paid. If it did not, call again and ask why.
This sounds cautious, but it prevents the frustration of discovering months later that your extra payment was held as a credit or applied to interest instead of principal.
Frequently Asked Questions
Will making one extra payment per year cut my loan in half?
No. One extra payment per year shortens a 30-year loan by roughly 4 to 5 years, not 15 years. To cut the loan in half, you would need to make roughly 6 to 8 extra payments per year, or refinance to a 15-year term. One payment is a meaningful reduction, but not a dramatic one.
Does it matter if I make the extra payment at the beginning or end of the year?
Yes, slightly. An extra payment made in January prevents interest for 12 more months than one made in December. The difference is roughly one month of interest savings, which is small compared to the total savings but still worth timing if you have the choice. Early in the year is always better.
Can I make extra payments if I am behind on my mortgage?
No. If you are behind, your lender will explore any payment above the minimum to catch you up on missed payments, not to principal. Get current first, then start making extra payments. If you are struggling to make regular payments, contact your lender about a loan modification or forbearance before attempting extra payments.
What if my lender will not let me make extra payments?
This is rare on mortgages, but some older loans or certain loan types may restrict prepayment. Check your loan documents for a prepayment penalty clause. If one exists and your lender enforces it, the cost of the penalty may outweigh the interest savings. In that case, focus on other debt first and revisit the mortgage once the restriction expires or you refinance.
Is making one extra payment better than investing the money instead?
It depends on what you could earn by investing. If you can reliably earn more than your mortgage interest rate in the stock market or bonds, investing might return more money. But mortgage interest is may provide, while investment returns are not. Many people find the certainty of mortgage savings more valuable than the possibility of higher investment returns, especially early in the loan.