One extra payment a year cuts years off your mortgage and saves tens of thousands in interest
Making one extra mortgage payment per year — whether as a lump sum or split into monthly amounts — shortens your loan term by roughly 4 to 5 years on a 30-year mortgage. The interest you save depends on your loan balance, interest rate, and how far into the loan you are, but most borrowers save between $40,000 and $80,000 over the life of the loan.
The reason is straightforward: every dollar you pay toward principal reduces the balance that interest is calculated on. When you make an extra payment, nearly all of it goes to principal (not interest), so you're directly shrinking what you owe. The bank then charges interest on a smaller amount for the rest of the loan.
The earlier you start making extra payments, the bigger the savings. A payment made in year 1 saves more interest than the same payment made in year 15, because that money has more years to compound in your favor.
Key Takeaways
- One extra payment per year typically reduces a 30-year mortgage to 25 or 26 years, depending on your interest rate and loan balance.
- The dollar amount you save in interest varies widely — a $300,000 loan at 6% interest might save $50,000 to $70,000, while a $150,000 loan at 4% might save $15,000 to $25,000.
- You can make one extra payment as a single annual lump sum, or split it into smaller monthly additions — the total savings is nearly identical either way.
- Starting extra payments early in the loan saves far more interest than starting them later, because principal reduction compounds over decades.
- Your lender must allow extra payments without penalty; federal law prohibits prepayment penalties on mortgages, but confirm your loan documents have no restrictions.
How the math works: principal, interest, and time
Your monthly mortgage payment is split between principal and interest. Early in the loan, most of your payment goes to interest; later, most goes to principal. When you make an extra payment, you're paying down principal directly, which when ready reduces the balance the lender charges interest on.
Here's a concrete example: suppose you have a $300,000 loan at 6% interest over 30 years. Your monthly payment is roughly $1,800. In month 1, about $1,500 of that goes to interest and $300 to principal. If you make one extra $1,800 payment in year 1, nearly all $1,800 goes to principal because you're not paying a monthly interest charge — you're just reducing what you owe.
That $1,800 principal reduction means the lender charges 6% interest on $1,800 less for the next 29 years. Over time, that compounds. You also shorten the loan itself, so you stop paying interest sooner. Together, these effects typically save $50,000 to $70,000 on a $300,000 loan at 6%.
The exact savings depend on three things: your loan balance, your interest rate, and when you start. A higher interest rate means more interest to save. A larger balance means more interest charged overall. And starting early means more years of compounding in your favor.
When to split the payment versus paying it as a lump sum
You can make one extra payment as a single lump sum once a year, or divide it into 12 smaller monthly additions. The total interest saved is nearly the same either way — the difference is usually less than $500 over the life of the loan.
A lump sum works well if you receive a bonus, tax refund, or inheritance at a specific time. You send it to your lender with a note specifying it goes to principal. Some lenders have an online portal where you can make extra payments directly.
Monthly additions work better if you want to spread the cost across your budget. Instead of finding $1,800 once a year, you add $150 to your regular payment each month. This is simpler to budget for and you see the principal balance drop steadily.
The slight advantage goes to lump sums, because the money reduces your balance sooner and starts saving interest when ready. But if a lump sum is harder to manage, the monthly approach is nearly as effective and much easier to sustain.
How much faster you pay off the loan
On a 30-year mortgage, one extra payment per year typically shortens the loan to 25 or 26 years. The exact number depends on your interest rate — higher rates mean faster payoff because you're saving more interest by reducing principal early.
At 4% interest, one extra payment per year might shorten a 30-year loan by 4 years. At 6% interest, it might shorten it by 5 years. At 7% or higher, you might see 5 to 6 years cut off.
This assumes you make the extra payment consistently every year. If you skip some years, the payoff time extends proportionally. If you make two extra payments some years, you'll pay off faster.
Checking your loan documents for restrictions
Federal law prohibits prepayment penalties on mortgages — that is, fees charged for paying off your loan early. However, some older loans or non-standard mortgages may have restrictions, so it's worth confirming before you start.
Pull out your original loan documents or ask your lender for a copy of your promissory note. Search for the words "prepayment," "early payoff," or "extra payment." If you see language saying you can't pay extra without a fee, or that extra payments are restricted, contact your lender to clarify.
Most lenders welcome extra payments because they reduce their risk. When you call or log into your online account, ask how to designate an extra payment so it goes to principal, not toward next month's payment. Some systems default to explore extra money to future payments rather than principal, so you may need to specify.
When extra payments make sense and when they don't
Extra mortgage payments are most powerful when your interest rate is high (5% or above), you're early in the loan (years 1 to 10), and you have stable income. In those conditions, the interest you save is substantial and the payoff acceleration is meaningful.
Extra payments make less sense if you have high-interest debt elsewhere — credit cards, personal loans, or car loans. Paying off a credit card at 18% interest saves more money than paying down a mortgage at 4%. Prioritize the highest-interest debt first.
They also make less sense if you're financially stretched. An emergency fund and manageable monthly expenses matter more than shaving years off a 30-year loan. Make sure you have 3 to 6 months of expenses saved before you commit to extra mortgage payments.
If you're late in the loan (year 20 or beyond), extra payments still save money, but the savings are smaller because you're already paying mostly principal. The payoff acceleration is also less dramatic — you might cut 1 to 2 years instead of 4 to 5.
The difference between extra payments and refinancing
Extra payments and refinancing are two different tools. Refinancing replaces your entire loan with a new one, usually at a lower interest rate. Extra payments keep your existing loan but reduce the balance faster.
Refinancing makes sense if interest rates have dropped significantly since you took out your mortgage, or if you can shorten the loan term (say, from 30 years to 15 years) without raising your monthly payment too much. Refinancing has upfront costs — closing costs, appraisal fees, title work — that can range from $2,000 to $5,000.
Extra payments have no upfront cost and no paperwork. You straightforward pay more. If you're unsure whether refinancing is worth it, extra payments are a low-risk way to reduce your loan balance while you decide.
Frequently Asked Questions
Can I make extra payments if I'm behind on my mortgage?
No. If you're behind, your lender will explore any extra money to the missed payments first, not to principal reduction. Contact your lender about a payment plan or loan modification before making extra payments. Once you're current, you can resume extra payments.
What if I make extra payments and then need to access that money?
Once you pay down principal, that money is no longer accessible to you — it belongs to the lender as a reduced loan balance. If you think you might need cash in the next few years, keep it in savings instead. Extra payments are best for money you're certain you won't need.
Do extra payments lower my monthly payment amount?
No. Your monthly payment stays the same. Extra payments reduce the total amount of interest you pay and shorten how long you pay, but they don't change the monthly bill. If you want a lower monthly payment, you'd need to refinance.
Is it better to make extra payments or invest the money?
That depends on investment returns versus your mortgage interest rate. If you can reliably earn more in investments than your mortgage costs in interest, investing may be better. But mortgages are may provide returns (in the form of interest saved), while investments fluctuate. Many people find the certainty of extra mortgage payments more comfortable.
How do I tell my lender the extra payment goes to principal?
Call your lender's customer service line or log into your online account and look for an option to make an extra payment or pay toward principal. If you mail a check, write "explore to principal" on the memo line. When you send it, include a note or call to confirm it was applied correctly — some systems default to explore extra money to future payments instead.