One extra payment per year saves you roughly 4 to 6 years of payments and tens of thousands in interest

A single extra mortgage payment made once per year does not sound like much, but it compresses your loan timeline significantly. On a 30-year mortgage, one extra payment annually typically shortens the loan by 4 to 6 years and saves between $40,000 and $80,000 in interest, depending on your loan size, interest rate, and how early you start. The exact savings depend on your specific numbers — a $300,000 loan at 6% interest behaves differently than a $150,000 loan at 4% — but the pattern holds across most mortgages.

The reason is straightforward: that extra payment goes directly to principal, not interest. When you pay down principal faster, you owe less money for the remaining life of the loan, which means less interest accrues. The earlier you start making extra payments, the more compounding works in your favor.

Key Takeaways

  • One extra payment per year typically shortens a 30-year mortgage by 4 to 6 years and saves $40,000 to $80,000 in interest, though the exact amount depends on your loan balance and rate.
  • The extra payment must go to principal, not interest — confirm with your lender that the payment is applied correctly and does not simply prepay next month's interest.
  • Making extra payments early in the loan saves more interest than making them late, because you reduce the principal balance when interest charges are highest.
  • Splitting one payment into 12 monthly additions ($1/12 of a payment each month) produces nearly the same result as one lump sum, but a true extra payment once yearly is simpler to track.

How the math works on a typical loan

Take a $300,000 mortgage at 6% interest over 30 years. Your monthly payment is roughly $1,799. Without extra payments, you pay about $647,500 total over the life of the loan — that is $347,500 in interest alone.

Now add one extra $1,799 payment per year. That extra payment goes straight to principal. In year one, you owe $299,201 instead of $298,400 at the end of the year. In year two, the interest calculation starts from a lower balance. This compounds. By year 24 or 25, your loan is paid off instead of year 30. You save roughly $70,000 in interest and 5 to 6 years of payments.

The savings scale with your loan size and rate. A $150,000 loan at 4% interest saves less in absolute dollars but the same proportion of time. A $500,000 loan at 7% interest saves more. The point is that the extra payment always works — it always reduces both the total interest paid and the number of years you carry the debt.

When to make the extra payment matters

The timing of extra payments within the loan term changes how much interest you save. An extra payment made in year 1 saves more interest than an extra payment made in year 20, because the principal balance is higher early on and interest charges are larger.

If you make one extra payment per year for all 30 years, you save the most. If you make extra payments only in the first 10 years, you still shorten the loan and save significant interest, but not as much as if you continued. If you wait until year 20 to start, the loan still shortens, but the savings are smaller because you have already paid most of the interest.

This is why starting early matters: the sooner you reduce principal, the sooner that lower balance stops generating interest charges.

Lump sum versus spreading the payment across the year

You can make one extra payment as a single lump sum once per year, or you can divide it into 12 smaller payments and add a portion to each monthly bill. Both work, but they produce slightly different results.

A true lump sum — one full payment made at a single point in the year — reduces principal by the full amount at that moment. If you make it in January, that principal reduction saves interest for the entire remaining year. If you make it in December, it saves interest for only the final month before the next year begins.

Splitting the payment into 12 monthly additions ($1,799 ÷ 12 = roughly $150 extra per month) produces nearly the same result, with a slight advantage because you reduce principal gradually throughout the year rather than all at once. The difference is usually small — a few hundred dollars over the life of the loan — so choose whichever method fits your cash flow better.

Confirm the payment goes to principal, not next month's interest

Before you make an extra payment, contact your lender and ask how to ensure it goes to principal. Some lenders automatically apply extra payments to principal; others apply them to next month's interest and principal combined, which delays the benefit. A few older systems may even hold the payment and apply it to future months, which wastes the advantage entirely.

When you make the payment, include a note or call the lender to specify: "Apply this payment to principal only." Some lenders have a checkbox or code you can use online or by phone. Confirm in writing that the payment was applied correctly — check your next statement to verify the principal balance dropped by the amount you paid.

If your lender does not allow you to direct extra payments to principal, or if they charge a fee for extra payments, consider whether the savings justify the cost. Most lenders do not charge, but some mortgage products (particularly certain FHA or VA loans) may have restrictions.

Compare extra payments to other uses of that money

One extra mortgage payment per year saves you tens of thousands in interest, but it is not the only use for that money. Before committing to extra payments, consider your other financial priorities.

If you carry high-interest debt — credit cards, personal loans, car loans above 6% — paying those down first usually saves more money than extra mortgage payments. If you have no emergency fund, building one to 3 to 6 months of expenses is more important than accelerating your mortgage payoff. If you have not maxed out retirement contributions, the tax advantage of retirement savings may outweigh the interest savings from extra mortgage payments.

That said, if your other debts are paid, your emergency fund is solid, and you have money left over, extra mortgage payments are a straightforward way to reduce both interest and the years you carry the loan.

What happens if you stop making extra payments partway through

You do not have to commit to extra payments for the entire 30 years. If you make extra payments for 5 years and then stop, the loan still shortens and you still save interest — just less than if you had continued. Your loan will not revert to the original 30-year timeline; it will simply take longer to pay off than if you had made extra payments the whole time.

This flexibility matters if your income changes or your priorities shift. You can make extra payments when you have the cash and pause when you do not, and you will still benefit from the payments you did make.

Frequently Asked Questions

Does making one extra payment per year affect my credit score?

No. Paying down your mortgage faster does not hurt your credit. It may slightly improve your credit utilization ratio (the amount of available credit you use), but the effect is minor. Your credit score cares about whether you pay on time, not whether you pay extra.

Can I make extra payments if I have an adjustable-rate mortgage?

Yes. Extra payments reduce your principal balance regardless of whether your rate is fixed or adjustable. When your rate adjusts, your new payment is calculated on a lower balance, which saves you money on the new rate as well.

What if I want to pay off my mortgage in 15 years instead of 30 — is one extra payment per year enough?

No. One extra payment per year shortens a 30-year loan by roughly 5 years, leaving you with about 25 years remaining. To reach a 15-year payoff, you would need to make roughly one extra payment every 6 months, or refinance into a 15-year mortgage from the start.

Do I lose the extra payment if I refinance?

No. When you refinance, the principal balance you have paid down stays paid down. Your new loan is based on the remaining balance, not the original loan amount. The extra payments you made reduce what you owe going into the refinance.

Is there a penalty for paying off my mortgage early?

Most mortgages do not have prepayment penalties, but some do — particularly certain FHA loans or mortgages from the 1990s and early 2000s. Check your loan documents or contact your lender to confirm. If a penalty exists, calculate whether the interest savings from extra payments exceed the penalty cost.