"Shark Tank" investor Kevin O'Leary has said the ideal age to be debt-free is 45, especially if you want to retire by age 60.
Being debt-free — including paying off your mortgage — by your mid-40s puts you on the early path toward success, O'Leary argued. It helps you free yourself from financial obligations at a time when your income is presumably stable and potentially even growing. You can ramp up your savings so you can ensure a comfortable life in retirement.
"Most careers start in early 20s and end in the mid-60s," O'Leary said in the 2018 interview with CNBC Make It. "So, when you're 45 years old, the game is more than half over, and you better be out of debt, because you're going to use the rest of the innings in that game to accrue capital."
While O'Leary's advice may resonate with some, Rachel Sanborn Lawrence, advisory services director and certified financial planner at Ellevest, says that aiming to be debt-free by 45 may be ill-advised. Not only is it unrealistic for many — it might also mean you leave money on the table.
Ahead, CNBC Select spoke to Sanborn Lawrence about who should be most cautious about heeding O'Leary's advice, and why.
If being debt-free in your mid-40s sounds like a dream, that's understandable. Debt can often feel weighty, especially when it's in the five- and six-figures. For many consumers who graduate with student loan debt in their early 20s, the thought of carrying that debt around for decades can be anxiety-inducing. Not to mention, you might be concerned that your debt can disqualify you from homeownership or other financial milestones (which is often not the case).
But mathematically, there's not always an incentive to be debt-free so soon, argues Sanborn Lawrence. If the interest rates on your debt are below 5% to 10%, it often makes most sense to invest your extra cash in the stock market, which has historically earned at above this rate, rather than rushing to pay off debt.
Mortgages, for instance, are at historic lows right now, so someone with an interest rate at 3% or below shouldn't feel pressed to pay off their home quickly and instead let their money grow in the market.
"If you are borrowing money at a lower rate than you're able to make on that money, you're going to end up net positive," says Sanborn Lawrence.
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Because of the gender wage gap, women, and especially women of color, should be extra cautious about O'Leary's advice, argues Sanborn Lawrence.
While O'Leary acknowledged that people's earning potential is linked to their age, he did not necessarily factor in how earning potential peaks for different groups at different times in their lives. Sanborn Lawrence calls this trend the "salary curve gap," and she argues it should influence the way people save and invest.
Men's salaries tend to peak at age 55, according to Sanborn Lawrence — just five to 10 years before most people retire. Meanwhile, the salary peak for women tends to happen at around age 40.
To use O'Leary's metaphor, women just don't have that "last inning," says Sanborn Lawrence. Someone whose salary continues to grow between the ages of 45 to 60 might be able to frontload their debt payoff, but women can't necessarily count on these additional 15 years of salary increases. It's smart to account for these disparities and not be so focused on debt payoff that other goals, like saving, get pushed off.
"As women, we tend to need to save more earlier on in our career," says Sanborn Lawrence. That includes both an emergency fund and retirement investments in a 401(k) or IRA (or both).
Saving more in your earlier years means that women may have less money to use to aggressively tackle their debt.
However, this can be counterbalanced by keeping a holistic view of your finances, saving in smaller increments over time and being smart about how you leverage credit (as opposed to relying on cash assets).
"Our whole society is built on consumer debt," says Sanborn Lawrence. While you should steer clear of high-interest credit card debt, it's OK to use debt intentionally, including taking on a mortgage, using loans to pay for school or financing a car to get you to and from work.
As for the ideal age to debt-free, don't get too caught up in the comparison game, says Sanborn Lawrence. A good goal is to be debt-free by retirement age, either 65 or earlier if you want. If you have other goals, such as taking a sabbatical or starting a business, you should make sure that your debt isn't going to hold you back.
If you do plan to carry debt (such as a mortgage) past retirement age, it's important to work with a financial planner to make sure you have enough income to cover the cost and understand how this debt might affect your heirs.