One extra payment a year cuts roughly 4 to 5 years off a 30-year mortgage and saves $40,000 to $60,000 in interest
The exact savings depend on three things: your loan balance, your interest rate, and when you make the payment. A single extra payment made early in the loan (when most of your payment goes to interest) saves more than one made near the end. On a $300,000 mortgage at 6.5%, one extra $1,900 payment per year shortens the loan by about 4 years and cuts total interest paid by roughly $50,000. On a $400,000 mortgage at the same rate, the same payment pattern saves closer to $65,000 in interest.
The reason the savings are this large is that every dollar of principal you pay down stops accruing interest for the remaining life of the loan. When you make that extra payment in year 3 instead of year 30, that money works for you for 27 extra years. The earlier you start, the more dramatic the effect becomes.
Key Takeaways
- One extra mortgage payment per year typically shortens a 30-year loan by 4 to 5 years and saves $40,000 to $65,000 in interest, depending on your balance and rate.
- The timing of the extra payment matters: making it early in the loan saves more interest than making it late, because you reduce the principal that accrues interest for longer.
- A $1,900 extra payment on a $300,000 mortgage at 6.5% saves roughly $50,000 over the life of the loan.
- Making extra payments only makes financial sense if you do not have high-interest debt elsewhere or a low emergency fund.
How the math changes with different loan amounts and rates
The dollar amount you save scales with both your loan size and your interest rate. A higher rate means more interest is being charged each month, so paying down principal faster saves more. A larger loan means more total interest to avoid.
On a $250,000 mortgage at 5.5%, one extra annual payment saves roughly $30,000 to $35,000 in interest and cuts 3 to 4 years off the loan. On a $500,000 mortgage at 7%, the same pattern saves closer to $80,000 to $95,000. The relationship is not perfectly linear—a larger loan does not save proportionally more, because you are paying down a smaller percentage of the total balance each year—but the savings are still substantial.
If your rate is below 4%, the savings are real but smaller in percentage terms. A $300,000 mortgage at 3% loses roughly $25,000 to $30,000 in interest over the life of the loan if you make one extra payment per year, and the loan shortens by 3 to 4 years. At very low rates, the opportunity cost of tying up that money in your mortgage instead of investing it becomes worth considering.
When timing of the extra payment changes the outcome
Making the extra payment in January saves more interest than making it in December of the same year, because the principal reduction compounds for 11 extra months. Making it in year 1 saves far more than making it in year 20, because the reduced principal accrues interest for 20 fewer years.
If you make one extra payment per year consistently from year 1 onward, you shorten the loan by roughly 4 to 5 years total. If you make the same payment pattern but start in year 10, you shorten the loan by only 2 to 3 years, because you have already paid 10 years of interest on the full balance. The earlier you begin, the more powerful the effect.
This is why lump-sum payments—like a tax refund or bonus—are most effective when applied to principal as soon as you receive them, rather than held in savings or applied to future payments.
The real cost: what you give up by making extra payments
Money you put toward your mortgage is money you cannot invest, spend, or keep as emergency reserves. If you have credit card debt at 18% interest, paying down your mortgage at 6% is mathematically the wrong move—the credit card interest is costing you more. If you have no emergency fund, making extra mortgage payments leaves you vulnerable to unexpected costs that force you to borrow at a higher rate later.
If you could invest that $1,900 per year in a diversified portfolio earning 7% to 8% annually, and your mortgage rate is 5.5%, you would come out ahead by investing rather than paying down the mortgage. The math shifts based on what you could earn elsewhere and what your actual risk tolerance is.
Mortgage interest is also tax-deductible if you itemize deductions (though fewer people do since the 2017 tax code change). If you are in the 24% federal tax bracket and deduct mortgage interest, your true cost of a 6% mortgage is closer to 4.56%. That changes the comparison between paying down the mortgage and other uses of the money.
How to structure extra payments so they actually reduce principal
Not all extra payments are treated the same way by your lender. If you send in an extra $1,900 without specifying how it should be applied, some servicers will hold it as a prepayment credit and explore it to your next regular payment, which does not reduce principal faster. Others will explore it to principal when ready.
To may support your extra payment reduces principal: write "explore to principal" on the check or in the payment memo if paying online, or call your servicer before sending the payment and confirm in writing how they will handle it. Some servicers have a specific process for principal-only payments; ask what it is. If your servicer resists or cannot confirm, send a follow-up letter via certified mail documenting your instruction.
Biweekly payment plans (paying half your monthly payment every two weeks instead of the full amount once a month) accomplish the same goal without requiring extra cash, because you end up making 26 half-payments per year instead of 24, which equals 13 full payments instead of 12. However, some servicers charge a fee to set up biweekly payments, so confirm the cost before enrolling.
When extra mortgage payments make the most sense
Extra payments are most valuable if you have a mortgage rate above 6%, no high-interest debt, a full emergency fund (3 to 6 months of expenses), and no other financial goals competing for that money. They are also sensible if you plan to stay in the home long enough to benefit from the shortened timeline—generally at least 5 to 7 years.
Extra payments are less useful if your rate is below 4%, you have credit card or student loan debt, your emergency fund is thin, or you are saving for a major purchase or life change in the next few years. In those cases, the money is usually better spent elsewhere.
If you receive a windfall—a bonus, inheritance, or tax refund—and you are not sure whether to put it toward the mortgage, ask yourself: do I have 6 months of expenses in savings? Do I have any debt above 6% interest? If the answer to either is no, that money should go there first. If both answers are yes, putting the windfall toward principal is a reasonable choice.
Frequently Asked Questions
Does making one extra payment a year actually shorten the loan by 4 years, or is that an estimate?
It is an estimate that varies based on your exact balance, rate, and when you make the payment. The range is typically 3 to 5 years for a 30-year loan, depending on those factors. You can calculate your specific outcome using a mortgage payoff calculator that lets you input extra principal payments.
What if I can only afford an extra payment every other year instead of every year?
You will see roughly half the benefit—shortening the loan by 2 to 2.5 years instead of 4 to 5, and saving $20,000 to $30,000 in interest instead of $40,000 to $60,000. The math scales proportionally, so any extra principal payment helps, even if you cannot do it every year.
Is it better to make one big extra payment a year or split it into monthly amounts?
One lump sum early in the year saves slightly more interest than splitting it into 12 smaller monthly payments, because the principal reduction compounds for longer. The difference is small—usually a few hundred dollars over the life of the loan—so the best approach is whichever one you can actually stick to.
Can I stop making extra payments if my financial situation changes?
Yes. Extra payments are voluntary and do not lock you into anything. If you lose income or face an unexpected expense, you can return to making only your regular monthly payment. The principal you have already paid down stays paid down.
Should I make extra mortgage payments if I am close to paying off the loan?
If you have fewer than 5 years left on the mortgage, the interest savings from one extra payment become smaller because there is less time for the principal reduction to compound. At that point, the money might be better used elsewhere—but if you are already on track and the extra payment does not strain your budget, it will still shorten the loan by a few months.