When Paying Down the Mortgage Beats Investing

One of the more common questions we field from clients is “Rather than investing, should I pay down my mortgage?” For most of the last fifteen years, the answer was relatively simple: Don't pre-pay your mortgage. When mortgage rates were at 3% or 4%, even a relatively conservative balanced portfolio had a reasonable shot at beating that hurdle over time, and cheap fixed-rate debt was something to hold onto, not rush to eliminate.

That math has changed. Freddie Mac's weekly survey put the average 30-year fixed rate at 7.28% as of October 1, 2026, the highest level since a brief period in late 2023 and up from 6.34% a year earlier. If you bought a home, moved, or refinanced in the last few years, there is a good chance your own rate is in that neighborhood. Now that we are seeing mortgage rates north of 7%, the old rule deserves a second look.

A guaranteed return, with no risk attached

Looking at this issue requires a change in the way we Every extra dollar you put toward principal earns exactly your mortgage rate, guaranteed. On a 7.25% loan, prepaying is the equivalent of buying an investment that pays 7.25% a year, with no market risk, no credit risk, and no bad years.

No other investment offers that combination today. The 10-year Treasury, the benchmark for "safe" money, has climbed to around 5%, which is attractive by recent standards. But Treasury interest is taxable at the federal level, and most bond and CD interest is taxable at both the federal and New York State level.

Consider a homeowner in the 24% federal bracket who also pays roughly 6% in New York State income tax, and who takes the standard deduction (so their mortgage interest saves them nothing on taxes). For this investor, paying down their mortgage is akin to receiving a 7.25% “risk-free” return, while investing in a taxable CD at 5% yields an after-tax return of approximate 3.5%. To match the mortgage payoff after taxes, a taxable investment would need to earn roughly 10% a year, every year. Stocks have done that in some periods (notably over the last decade) but have fallen short in many others. Paying down the mortgage delivers these “returns” without the accompanying risk of an aggressive equity investment.

First, know where you stand

This strategy depends entirely on your own rate, not the headline rate. Plenty of Long Island homeowners locked in at 3% or less during 2020 and 2021. If that's you, keep paying on schedule: Even a 5% Treasury Bond or a high-yield savings account likely beats your loan, and that cheap debt is a genuine asset.

The case for prepaying is strongest for:

Homeowners who bought or moved in the last two to three years and carry a rate of roughly 6.5% or higher.

Anyone with an adjustable-rate mortgage or home equity line that has reset higher.

Retirees or near-retirees who took on a new mortgage when downsizing, relocating, or helping family, and now carry it into retirement.

A rough rule of thumb: The higher your rate and the more conservative your investment mix, the more prepayment makes sense. A 7% mortgage is a much easier hurdle for an aggressive stock portfolio to beat than for a portfolio that is mostly bonds and cash.

What about the mortgage interest deduction?

For many households, the deduction is worth less than people assume. Mortgage interest only helps if you itemize, and with today's large standard deduction, most retirees, especially those with smaller balances, no longer do.

Long Island is a partial exception. Our property taxes are high, and the federal cap on state and local tax (SALT) deductions was raised to roughly $40,000 starting in 2025, though it phases down for higher earners and is scheduled to revert later this decade. Some homeowners who stopped itemizing may now be back in that camp.

If you do itemize, the way to think about the interest deduction is that it lowers your effective mortgage rate. At a 24% bracket, a 7.25% loan costs closer to 5.5% after the federal deduction, which narrows the gap with safe investments. It's worth running your own numbers with your tax preparer before making an assumption either way.

When to keep investing instead

Prepaying a mortgage is a good use of extra money, not of all money. Before sending a dollar of extra principal, make sure these boxes are checked:

Capture the full employer match. A 401(k) match is an immediate 50% or 100% return. Nothing beats it.

Keep a real emergency fund. Money sent to your lender is hard to get back. You can't withdraw home equity in a pinch without selling, refinancing at today's rates, or qualifying for a home equity loan, which banks tighten exactly when times are tough.

Pay off costlier debt first. Credit cards, personal loans, and many car loans charge more than a 7% mortgage.

Don't starve tax-advantaged accounts. Roth and pre-tax contributions carry tax benefits that a mortgage payoff doesn't. A blended approach often works best.

Watch your concentration. For many families the home is already the largest asset. Pouring more into it ties up net worth in one illiquid, undiversified place.

There is also a refinancing wrinkle. If rates fall meaningfully over the next few years, a 7% borrower may be able to refinance, and prepayments made now will have earned 7% only for as long as the old rate lasted. That's not a reason to avoid prepaying, but it's a reason not to strip your liquid savings to do it.

For retirees: Where the money comes from matters

For those in or near retirement, a paid-off home can be enormously valuable. It lowers the income you need each month, which can mean smaller withdrawals, less sequence-of-returns risk, and real peace of mind. That last point is particularly important- our homes are more than numbers on a spreadsheet- they carry a lot of psychological and emotional baggage. Whenever we are dealing with an emotionally charged financial decision it makes sense to proceed with caution and to possibly bring in an outside expert. At the same time, the psychological relief of removing some of the overhang of mortgage debt has a value; It’s just important to know that this can come at a cost.

Importantly, the source of the prepayment matters as much as the decision itself. Pulling a large lump sum from a traditional IRA or 401(k) to wipe out a mortgage can push you into a higher tax bracket, raise your Medicare premiums through IRMAA two years later, and make more of your Social Security taxable. Selling appreciated stock in a taxable account can trigger capital gains. In many cases, a steady stream of extra payments out of cash flow, or redirecting money that would otherwise go to bonds or CDs, accomplishes the goal without the tax bill.

A few practical ways to do it:

Add extra principal each month. Even a few hundred dollars meaningfully shortens a 30-year loan. Make sure your servicer applies it to principal, not to the next payment.

Ask about a recast. Many lenders will re-amortize your loan after a lump-sum paydown for a modest fee. Your rate stays the same, but your required monthly payment drops, which improves cash flow without giving up flexibility.

Treat it as part of your fixed-income allocation. If you'd otherwise buy a bond yielding 5%, consider whether that money is better used retiring 7% debt, and adjust the rest of your portfolio accordingly.

The bottom line

When your mortgage costs 7% or more, paying it down is no longer the timid choice. It's a guaranteed, risk-free return that most safe investments can't match after taxes. That doesn't mean abandoning your portfolio: keep the match, keep the emergency fund, keep investing for growth. But for the dollars you'd otherwise park in bonds or CDs, your own mortgage may be the best place for them.

The right mix depends on your rate, your tax picture, your liquidity, and how close you are to retirement. That's a conversation worth having with your advisor and tax professional before you write the first extra check.

This article is for general informational purposes only and is not individualized investment, tax, or legal advice. Examples are hypothetical and simplified; individual results will vary. Consult your tax professional regarding your specific situation. Securities offered through Osaic Wealth, Inc., Member FINRA/SIPC. Great South Bay Advisors is separately owned, and other entities and/or marketing names, products, or services referenced here are independent of Osaic Wealth.