Why Early Principal Matters So Much
A mortgage payment is fixed, but the split between interest and principal isn't. On a $300,000 loan at 6.75%, the payment is $1,946. In the first month, $1,687.50 of that is interest (6.75% ÷ 12 × $300,000) and only $258.50 reduces the balance. Over the whole first year you pay $23,352, and the balance falls by only about $3,200.
Interest is charged on whatever balance remains, so principal you pay off early stops collecting interest for every month left on the loan. That's why the strategies below work best when you start early. For the full math, with savings tables and how payoff dates are calculated, see how much extra mortgage payments save.
All examples use the same loan: $300,000 at 6.75%, 30 years, $1,946/month, the default in our Loan Payoff Calculator.
1. Round Up Your Payment
Round the payment up to a clean number and tell your servicer to apply the difference to principal. It's the easiest habit to keep because the change barely shows in your budget.
- $1,946 → $2,000 (+$54/month): paid off about 2 years 5 months sooner, saving about $38,000 in interest
- $1,946 → $2,100 (+$154/month): paid off about 5 years 9 months sooner, saving about $91,000
Pros: painless, automatic. Cons: small amounts work slowly. You'll need to go bigger to cut a decade off.
2. Add a Fixed Extra Payment Every Month
Choose a set amount, automate it, and raise it when your income goes up. Consistency is what makes this work. $200/month extra pays the loan off in about 276 payments instead of 360, roughly 7 years sooner, and saves about $110,000 in interest. That's on $55,200 of extra payments in total.
Pros: predictable, and you can stop any time without penalty (unlike a higher required payment). Cons: it takes discipline, and money sent to the loan isn't easy to get back.
3. Switch to Biweekly Payments
Pay half your monthly payment every two weeks. That's 26 half-payments a year, which equals 13 full payments: one extra monthly payment per year. On our example loan that pays the mortgage off about 6 years sooner and saves roughly $91,000–$95,000 in interest. The exact figure depends on whether your servicer applies the money every two weeks, monthly, or once a year.
- Do it yourself: add 1/12 of your payment (about $162) as extra principal every month. You get nearly the same result with no program fees.
- Watch out: some third-party biweekly programs charge setup fees, or hold your half-payments and apply them only once a month. Confirm that the extra goes to principal.
Pros: it fits a biweekly paycheck. Cons: it's no better than paying the same extra amount monthly, and fees can eat into the savings.
4. Put Windfalls Toward Principal
Tax refunds, bonuses, and inheritances can all go toward a lump-sum principal payment. When you pay matters: the earlier the payment, the more months of interest it removes.
| Lump Sum | Paid In | Interest Saved | Time Saved |
|---|---|---|---|
| $5,000 | Year 1 | ~$30,600 | 1 yr 6 mo |
| $10,000 | Year 1 | ~$58,000 | 2 yr 11 mo |
| $10,000 | Year 10 | ~$28,700 | 1 yr 8 mo |
| $10,000 | Year 20 | ~$10,300 | 10 mo |
Pros: no ongoing commitment. Cons: windfalls are irregular, and a big lump sum leaves you with less cash on hand.
5. Recast After a Large Payment
A recast (re-amortization) works like this: you make a large principal payment, often with a $5,000–$10,000 minimum, and the lender recalculates your payment on the lower balance. The rate and payoff date stay the same. There's no credit check or appraisal, and the fee is usually a few hundred dollars.
Example: five years in, your balance is about $281,600. You pay $20,000 and recast. Your required payment drops from $1,946 to about $1,808. If you keep paying $1,946 anyway, the loan is paid off about 4 years early.
Pros: a lower required payment gives you flexibility. Cons: recasting itself doesn't shorten the loan. It lowers the payment. FHA, VA, and USDA loans generally can't be recast.
6. Refinance to a Shorter Term
Shorter loans usually come with lower rates, and the payment pays down principal much faster. Compare a $300,000 loan over different terms (example rates):
- 30-year at 6.75%: $1,946/month, about $400,000 total interest
- 20-year at 6.25%: $2,193/month, about $226,000 total interest
- 15-year at 6.00%: $2,532/month, about $156,000 total interest
The 15-year saves about $245,000 in interest but costs $586 more every month, and that payment is required. Refinancing also has closing costs, typically 2–5% of the loan, so you need to stay in the home long enough to break even. Our refinance calculator works that out. Many borrowers get most of the benefit by keeping the 30-year loan and voluntarily paying the 15-year amount.
Pros: the lowest total interest, and the plan is locked in. Cons: closing costs, and no flexibility if your income drops.
7. Drop PMI and Redirect It
If you pay private mortgage insurance on a conventional loan, you can ask to cancel it once your balance reaches 80% of the home's original value. It ends automatically at 78% on the original schedule. Extra principal payments get you there sooner. Then send the PMI money (often $100–$300/month) to principal. Some lenders also allow early removal based on a new appraisal. See what PMI is and how to remove it.
When NOT to Prepay Your Mortgage
- You carry high-interest debt. A credit card at 20%+ APR costs far more than a 6–7% mortgage. Pay it off first.
- You have no emergency fund. Home equity isn't cash. Keep 3–6 months of expenses liquid first, because you can't get prepaid principal back if you lose your job.
- You're missing a 401(k) match. An employer match is an instant 50–100% return on that money, which no mortgage payoff can beat.
- Your rate is low. Paying down a 6.75% loan earns a guaranteed 6.75%. At 3–4%, long-term investing has historically come out ahead, though it carries risk.
- You'll sell soon, or your loan has a prepayment penalty. Penalties are rare on modern mortgages, but check your note.
How to Make Sure It Counts
Always mark extra money as "apply to principal", either with the principal-only option in your servicer's portal or on the check memo. Then confirm on your next statement that the balance dropped by the extra amount. Otherwise some servicers treat the money as an early payment of next month's bill, which saves you nothing.
Which Strategy Fits You?
- Small, painless start: round up, or add 1/12 of your payment each month
- Steady budget: a fixed monthly extra amount
- Irregular income or bonuses: lump sums, recasting if you want a lower payment
- Fastest payoff and you can afford a higher required payment: refinance to 15 or 20 years
Most people combine a fixed monthly extra with windfalls as they come in. Plug your own numbers into the Loan Payoff Calculator to see your new payoff date.