How Extra Payments Shorten Your Mortgage (With Real Numbers)
See how extra monthly payments, a 13th payment or a lump sum cut years and interest off a mortgage, plus the prepayment penalty rules to check first.
By Awais, Founder and editor-in-chiefPublished
Every extra dollar you pay toward principal reduces the balance that interest is charged on, so the loan ends sooner and costs less. On a $300,000, 30-year mortgage at 7%, paying just $200 extra a month cuts about seven years off the loan and saves more than $116,000 in interest.
This guide shows the exact effect of three common strategies, explains why early payments matter most, and lists what to check with your lender first. It is general information, not financial advice.
Why extra payments work so well
Each month, your lender charges interest on the balance you still owe. Whatever is left of your payment after interest goes to principal.
Principal repaid = payment − interest this month
Take a $300,000 loan at 7% over 30 years. The fixed payment is $1,995.91. In month one, interest is $300,000 × 0.07 ÷ 12 = $1,750.00, so only $245.91 reduces the balance. Early in a mortgage, most of your payment is interest.
An extra payment goes entirely to principal (as long as it is applied that way). It also lowers the interest in every future month, which means more of each regular payment goes to principal from then on. The savings compound in your favor.
Strategy 1: Add a fixed amount every month
All figures below use the same $300,000 loan at 7% with a 30-year term. The baseline pays $418,527 in total interest over 360 months.
| Extra each month | Paid off in | Time saved | Total interest | Interest saved |
|---|---|---|---|---|
| $0 | 30 years | — | $418,527 | — |
| $100 | 25 years 10 months | 4 years 2 months | $349,189 | $69,338 |
| $200 | 22 years 11 months | 7 years 1 month | $301,887 | $116,640 |
| $500 | 17 years 4 months | 12 years 8 months | $218,291 | $200,235 |
The first $100 does the most work per dollar. Over the life of the loan, $100 a month adds up to about $31,000 of extra payments, and it saves $69,338 of interest.
Strategy 2: Make one extra payment a year
Paying a 13th payment each year is a popular habit. The simplest way is to add one-twelfth of your payment to every monthly payment: $1,995.91 ÷ 12 = $166.33 a month.
On the example loan, that pays the mortgage off in 23 years 9 months and saves $102,424 in interest.
You may have heard of biweekly payments: paying half your payment every two weeks. A year has 52 weeks, so you make 26 half-payments, which equals 13 full payments. The effect is roughly the same as the 13th-payment method above. Before signing up for a biweekly program, check whether there is a fee and whether the servicer applies each half-payment when it arrives or holds it until the full payment is collected. Adding the extra amount yourself is free.
Strategy 3: Pay a lump sum
A bonus, tax refund or inheritance can go straight to principal. Timing matters, because money paid early saves interest for longer.
| One-time $10,000 payment | Paid off in | Interest saved |
|---|---|---|
| In month 1 | 27 years | $62,662 |
| After 5 years (month 60) | 27 years 10 months | $43,092 |
The same $10,000 saves about $19,600 more if you pay it at the start rather than after five years.
Some lenders offer a recast after a large lump sum: they keep your end date but lower your monthly payment to match the new balance. That improves cash flow instead of shortening the loan. Ask whether your servicer offers it and what it charges.
Check these things first
1. Prepayment penalties
A prepayment penalty is a fee some lenders charge if you pay off all or part of the mortgage early. The CFPB notes that such penalties do not normally apply when you pay extra principal in small amounts, but read your own loan documents.
For most US home loans, federal rules limit penalties tightly. Under Regulation Z, section 1026.43(g), a penalty is allowed only on a qualified mortgage whose rate cannot increase and that is not a higher-priced loan. Even then it:
- cannot apply after the first three years
- is capped at 2% of the amount prepaid in the first two years, and 1% in the third year
- requires the lender to have offered you a loan option without a penalty
Your Loan Estimate and Closing Disclosure both say on page 1, in the Loan Terms section, whether the loan has a prepayment penalty and how much it could be.
If your loan is from another country, the rules differ. In India, for example, see our guide on how EMI is calculated for how part-prepayment changes a loan.
2. Make sure the money goes to principal
The CFPB says you may be allowed to make extra payments on principal and should make sure they are applied to principal rather than interest. Most servicers have a “principal only” field online or a line on the payment slip. Check your next statement to confirm the balance dropped by the full extra amount.
3. Private mortgage insurance
If you pay PMI, extra payments can bring forward the date you can ask to cancel it, which is when the balance reaches 80% of the home’s original value. A CFPB bulletin notes that extra payments do not move the date of automatic termination at 78%, which follows the original schedule. So once you reach 80%, ask in writing.
When extra payments may not be the best move
Paying down a mortgage is a guaranteed return equal to your interest rate. It is often a strong choice, but consider these first:
- Emergency savings. Money paid into a mortgage is hard to get back without selling or borrowing. Keep a cash buffer first.
- Higher-rate debt. Credit cards and personal loans usually charge more than a mortgage. Pay those down first; the loan calculator shows how fast.
- Employer retirement match. If your employer matches contributions, missing that match usually costs more than mortgage interest saves.
- Low-rate mortgages. If your rate is low, the guaranteed saving is small too, and other uses of the money may matter more.
Run your own numbers
Enter your balance, rate, remaining term and extra payment in the mortgage calculator to see your new payoff date and interest saved. If you are still choosing a loan, compare terms in our 15 vs 30-year mortgage guide: a 30-year loan with regular extra payments is one way to get some of the 15-year savings while keeping a lower required payment.
FAQ
Is it better to pay extra monthly or one lump sum a year?
Earlier is better, so a monthly extra slightly beats the same total paid at the end of the year. The difference is small; what matters most is paying extra consistently.
Does an extra payment lower my monthly payment?
Usually not. On a standard fixed-rate mortgage, extra payments shorten the loan but the required payment stays the same. A recast, if your lender offers one, is the way to lower the payment instead.
How much does $100 extra a month save on a mortgage?
On a $300,000, 30-year loan at 7%, it saves $69,338 in interest and ends the loan 4 years 2 months early. The saving is larger on higher rates and when you start earlier.
Can I skip a payment if I paid extra before?
Usually not. Money marked “principal only” reduces the balance but does not normally move your next due date. Ask your servicer how it applies extra money, and keep making the regular payment every month unless it confirms in writing that you are paid ahead.