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Should You Pay Off Your Mortgage Early or Invest?

Published October 14, 2026 · By the PrepayMath team

Not financial advice. This guide is for general education only. Examples use simplified assumptions (fixed rates, principal and interest only) and are not recommendations or rate quotes. Confirm details with your loan servicer, lender, or a licensed financial or tax professional before acting.

Few personal-finance questions spark more debate. One side says a paid-off house is peace of mind and a guaranteed return. The other says your money will grow faster in the market. Both can be right. It depends on your mortgage rate, what you'd realistically earn by investing, taxes and your tolerance for risk. This guide sets up a fair comparison and runs the numbers.

Setting up a fair comparison

To compare honestly, both strategies have to spend exactly the same money each month. Here's the setup our calculator uses:

• Prepay first: Put your extra cash toward principal every month. Once the mortgage is paid off, invest the entire freed-up amount (your old payment plus the extra) every month until the original payoff date.
• Invest first: Invest the extra cash every month and let the mortgage run its normal schedule.

At the original payoff date, both households own the home free and clear. The only difference is how much they have invested. We compare that balance after estimated tax on investment gains.

Worked example

A homeowner owes $300,000 at 6.5% with 25 years left and has an extra $500 a month. If they prepay, the mortgage is gone in about 15 years 11 months, and they then invest the full freed-up amount for the remaining nine years or so.

Here's how the two paths compare after 25 years at different assumed returns:

(Returns are held steady every year here, which real markets never do. Treat this as a way to see how the outcome responds to each assumption, not as a forecast.)

What the table tells us

The break-even is your mortgage rate, after tax. When the investment return exactly equals the mortgage rate and there's no tax, the two strategies tie to the dollar. That's the core insight. Prepaying earns a guaranteed return equal to your mortgage rate. Investing has to beat that rate after taxes to come out ahead.

Taxes move the line. We use 15% as an illustration because, according to the IRS, the tax rate on most net capital gain is no higher than 15% for most individuals, and some gains are taxed at 0%. ^[source] At a 7% return, a 15% tax on gains turns a roughly $21,000 win for investing into a dead heat. Investing inside tax-advantaged accounts such as a 401(k) or IRA can change the answer, and so can the mortgage interest deduction if you itemize ^[source], because it lowers your effective mortgage rate.

Low-rate mortgages strongly favor investing. With the same setup but a 3% mortgage, a 7% return and 15% tax, investing ends at about $366,780 versus about $256,234 for prepaying. When your mortgage is cheap, prepaying it gives up a lot of potential growth.

Where today's rates fit

For the week of October 8, 2026, the Freddie Mac Primary Mortgage Market Survey reported an average 30-year fixed rate of 7.40%. If you have a recent loan near that level, prepaying offers a guaranteed return in the 7% range, which is hard to reliably beat after taxes. If you locked in a rate around 3% years ago, the math leans toward investing for many people.

The parts the math doesn't capture

Risk. The prepayment return is certain. Investor.gov describes risk tolerance as your ability and willingness to lose some or all of your original investment in exchange for potentially greater returns. ^[source] Market returns aren't, and a bad decade, especially right before you need the money, can change the outcome. Risk-adjusted, prepaying is more valuable than the raw numbers suggest.

Liquidity. Invested money can be sold if you lose your job or face a big bill. Money in your home equity can only be reached by selling or borrowing, and lenders may be least willing to lend exactly when you need it. This is one reason many planners suggest building an emergency fund before prepaying. ^[source]

Behavior. The invest-first strategy only works if you actually invest the money every month and leave it alone. Prepaying is automatic discipline. Be honest about which you'll stick with.

Peace of mind. Being mortgage-free lowers your monthly costs for good, which can make early retirement or a career change feel more manageable. That has real value even if a spreadsheet can't price it.

Priorities that usually come first. Paying off high-interest debt and capturing any employer retirement match typically beat both options.

A middle path

You don't have to pick one. Many households split extra cash, for example half to principal and half to investments. That way you get some guaranteed return and some growth potential. You can model a split by entering the prepay portion in the extra payment calculator and comparing it with the invest results here. If you have a lump sum instead of monthly cash, a recast lets you prepay and still lower your required payment.

How to use the calculator step by step

1. Enter your current balance, rate and years remaining from your latest statement.
2. Enter the extra cash you could commit each month. Be realistic. The comparison assumes you put this amount toward one strategy every month without fail.
3. Choose an expected return. Start conservatively, then test a few higher and lower values. If the winner flips with small changes, the decision is close and the non-math factors should decide.
4. Set a tax rate on gains. Use 0% if you'd invest in a tax-advantaged account, or an estimate of your tax rate on investment gains for a taxable account.
5. Read the chart. It shows how each path's invested balance grows. The prepay path starts slowly and then rises steeply once the mortgage is gone.

Two example households

Household A bought recently with a rate near today's average, has a solid emergency fund, and is nervous about the market. Prepaying gives them a guaranteed return around their mortgage rate and a clear finish line. The math is close to a tie at moderate returns, and their risk preference tips it toward prepaying.

Household B locked in a 3% rate, has decades until retirement, and is comfortable with market swings. Their cheap mortgage makes prepaying a low-return use of cash, and in our example investing comes out more than $100,000 ahead. Investing first is likely the better fit, ideally in tax-advantaged accounts.

Quick rules of thumb

• Mortgage rate higher than your realistic after-tax return? Prepaying likely wins, with less risk.
• Mortgage rate well below it? Investing likely wins over long periods, with more risk.
• Close call? Let liquidity, risk tolerance and peace of mind decide, or split the difference.

Compare prepaying vs investing with your numbers →

Not financial advice. This guide is for general education only. Examples use simplified assumptions (fixed rates, principal and interest only) and are not recommendations or rate quotes. Confirm details with your loan servicer, lender, or a licensed financial or tax professional before acting.