One extra payment per year cuts roughly 4 to 7 years off a 30-year mortgage
The exact number depends on how much of your payment goes toward principal versus interest, which changes every month. Early in the loan, most of your payment covers interest, so an extra payment saves less time. Later, when more goes to principal, the same extra payment saves more time. A rough estimate: making 13 payments per year instead of 12 will shorten a 30-year mortgage by somewhere between 4 and 7 years, depending on your interest rate and how far into the loan you are.
The lower your interest rate, the more time you save. A 3% mortgage saves more years per extra payment than a 7% mortgage does, because more of each payment goes straight to principal rather than to interest. If you start early—in year one—you save more total time than if you start in year 10, because that extra principal compounds over decades.
Key Takeaways
- One extra mortgage payment per year typically reduces a 30-year loan by 4 to 7 years, with the exact number depending on your interest rate and when you start.
- Early extra payments save more time than late ones, because the principal reduction compounds over the remaining life of the loan.
- Lower interest rates mean each extra payment saves more years, because more of it goes to principal instead of interest.
- You can make one extra payment per year by paying one-twelfth more each month, or by making a lump sum payment once a year.
- Your lender must allow principal prepayment without penalty—check your note or call to confirm there is no prepayment clause.
Why the savings vary so much between loans
The reason the time saved is a range rather than a fixed number comes down to how mortgage interest works. On the first payment of a 30-year loan, you owe 30 years' worth of accumulated interest. Your lender calculates the interest you owe that month, subtracts it from your payment, and puts the rest toward principal. As the principal shrinks, the interest owed each month shrinks too.
An extra payment made in month one goes almost entirely to principal, because you have not yet paid down the balance. That principal reduction then compounds—it means less interest accrues in month two, which means more of month two's payment goes to principal, and so on. An extra payment made in month 300 also goes mostly to principal, but there is less loan left to compound against, so the total time saved is smaller.
Interest rate matters for the same reason. At 3%, you might pay $400 in interest and $200 in principal on a $600 payment. At 7%, the same $600 payment might be $350 interest and $250 principal. The 7% loan has less principal reduction per payment, so an extra payment saves fewer years.
How to calculate the exact number for your loan
Your mortgage statement or online account shows your current principal balance, interest rate, and remaining term. You can use an online mortgage payoff calculator—search "mortgage payoff calculator with extra payments"—and enter those three numbers plus the amount of your extra payment. The calculator will show you the new payoff date.
Most lenders also provide this information if you call and ask. Tell them your current balance and ask how many months remain if you make one extra payment per year. They can run the math in seconds. This is more accurate than an estimate, because it accounts for your exact rate and remaining balance.
If you want to understand the math yourself: each extra payment reduces your principal by that payment amount. The interest you save is the interest that would have accrued on that principal over the remaining life of the loan. The time saved is roughly the number of months it would have taken to pay down that principal at your normal payment rate—but it is not exact, because the interest calculation changes as the balance drops.
The difference between paying extra monthly versus once a year
Paying one-twelfth of an extra payment each month saves slightly more time than making one lump sum payment once a year. The difference is small—usually a few months over the life of the loan—because the monthly approach lets that extra principal start reducing interest when ready, rather than waiting 12 months.
For example, if your payment is $1,200, you could pay $1,300 every month (an extra $100), or pay $1,200 for 11 months and $2,400 in month 12. The monthly approach saves a bit more time, but the difference is not dramatic. Choose whichever method fits your budget and cash flow. Some people find it easier to make one larger payment once a year; others prefer spreading it across 12 months.
Make sure your lender allows you to specify that extra money goes to principal, not to next month's payment. Some lenders automatically explore overpayments to the next month's due amount instead. Call and ask, or check your account settings online. You want the extra money reducing your principal balance, not sitting in a payment buffer.
What to check before you start making extra payments
Read your mortgage note or call your lender and confirm there is no prepayment penalty. This is a fee some lenders charge if you pay off the loan early. Most mortgages issued in the last 15 years do not have one, but older loans sometimes do. If your note says you cannot prepay without penalty, you will need to decide whether the years saved are worth the fee—usually they are not.
Also confirm that your lender will let you direct the extra payment to principal. Some servicers have a setting you can change online; others require a written request or a note with your payment. A quick call to your lender's payment department takes five minutes and prevents the extra money from being misapplied.
If you have a variable-rate mortgage (an ARM), the calculation changes when your rate adjusts. The years saved depend on what your rate becomes. If you are considering extra payments on an ARM, recalculate the payoff timeline after each rate adjustment.
When extra payments make sense and when they do not
Extra mortgage payments make the most sense if your interest rate is higher than what you could earn elsewhere. If you have a 6% mortgage and could only earn 1% in a savings account, paying down the mortgage is the better move. If you have a 3% mortgage and could earn 5% in a high-yield savings account or invest in a diversified portfolio, the math may favor saving the extra money instead.
Extra payments also make sense if you are close to paying off the loan and want to own your home free and clear. The psychological benefit of being debt-free can be worth more than the math alone suggests.
Extra payments make less sense if you have high-interest debt (credit cards, personal loans) still outstanding. Pay those down first—the interest rate is usually much higher, and the math is clearer. They also make less sense if you do not have an emergency fund. A mortgage is low-interest debt; if you use all your extra money to pay it down and then face a job loss or major repair, you may end up borrowing at a much higher rate.
Frequently Asked Questions
If I make one extra payment in year 5, do I save the same amount of time as if I make it in year 1?
No. An extra payment in year 1 saves more time because the principal reduction compounds over 29 more years. An extra payment in year 5 compounds over 25 years. The difference is real but not enormous—maybe 6 months to a year depending on your rate. Starting early is better, but starting late is still worthwhile.
Does making extra payments hurt my credit score?
No. Paying down debt does not lower your score. Your score may shift slightly because the ratio of debt you owe to your credit limit changes, but the direction is neutral to positive. Paying on time and reducing debt are both good for your score.
Can I stop making extra payments if my situation changes?
Yes. Extra payments are voluntary. If you lose income or face an unexpected expense, you can go back to making your regular payment. The principal you paid down stays paid down, so you have still shortened the loan—you just will not shorten it further until you resume extra payments.
What if I want to pay off the mortgage in 15 years instead of 30?
You have two options: refinance into a 15-year mortgage (which raises your monthly payment but locks in a faster payoff), or make extra payments on your current 30-year mortgage until it is paid off. The extra-payment route gives you flexibility—you can adjust the amount or stop if needed. A refinance is more rigid but may offer a lower interest rate.
Does the lender have to tell me how much time I am saving?
No, but they will tell you if you ask. Call the payment department and give them your current balance and ask how many months remain if you make one extra payment per year. They can calculate it in minutes. You can also use an online calculator with your loan details.