Mark Cuban Says the Best Investment Is Paying Off Your Debt -- Is He Right? Each person's financial situation is different, so it is worth a closer look at when it's better to pay off debt or invest.

Billionaire investor and Shark Tank star Mark Cuban said that the safest investment you can make right now is to pay off your debt, according to an interview with Kitco News earlier this year.

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"The reason for that is whatever interest you have -- it might be a student loan with a 7 percent interest rate -- if you pay off that loan, you're making 7 percent," said Cuban. "And so that's your immediate return, which is a lot safer than trying to pick a stock, or trying to pick real estate or whatever it may be."

Cuban is mostly right: More often than not, paying down debt as fast as possible is going to provide the most value in the long run. And perhaps more importantly, it will do so without any real risk that comes with most investing. That said, each person's financial situation is different, so it is worth a closer look at when it's better to pay off debt or invest.

Debt is like investing but in reverse.

One important thing to note is that the same principals that make investing so important also make paying off your debt similarly crucial. As Cuban points out, the interest rate on your loan is essentially like the rate of return on your investments but backward. In fact, many investments are simply ways you're letting your money get loaned out to others in exchange for them paying interest.

As such, it's important to keep in mind that as satisfying as it might be to watch your money grow in investments, it's doing just the opposite when you have debt.

Every loan is different.

Although debt chips away at your net worth through interest, it's important to note that different types of borrowing do so in very different ways. Every loan is different, with some offering terms that are actually quite favorable and others that can be excessively costly.

An overdue payday loan can lay waste to your financial health in no time, but a 30-year fixed-rate mortgage with a competitive rate can be relatively easy to manage with good planning. Borrowers should be sure they understand what kind of debt they have and how it's affecting their finances.

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Focus on the interest rate.

The key factor to take note of when considering how to allocate funds is the interest rate -- usually expressed as your APR. Debt with a high APR is almost always going to be better to pay down before you focus on any other financial priorities beyond the most basic necessities.

The average APR on credit cards as of August 2018 was 14.38 percent. That's well in excess of what anyone can reasonably expect to sustain as a return on most investments, so it shouldn't be hard to see that investing instead of paying down your credit card is almost always going to cost you money in the long run.

Does your interest compound?

Another crucial factor in understanding how your debts and your investments differ is whether or not your interest is compounding. Compounding interest -- like that on most credit cards -- means that the money you pay in interest is added to the amount due and you'll then have to pay interest on it in the future. That can lead to debt snowballing and growing exponentially. So, not only do credit cards have high interest rates, but they also make for debt that's growing faster and faster unless you take action to pay it down.

However, that same principle can work in reverse. Gains on something like stocks will also compound over time, so there's a similar dynamic at work when comparing your investment returns to fixed interest costs.

Know your risk tolerance.

Another factor that plays a big part in the conversation is your level of risk tolerance. Note that the question Cuban was responding to earlier was about what the "safest" investment was. For most people, erring well on the side of caution when it comes to something like personal finance just makes sense, and in that case, focusing on paying off debt is pretty crucial.

However, others might decide that the long-term payoffs that are possible make it worth rolling the dice on their future. Borrowing money for investments is common despite the risks associated, with everyone from massive investment banks to investors with margin accounts opting to take a calculated risk that their returns will ultimately outpace the cost of borrowing.

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Costs of debt are set, investment returns often are not.

One important aspect of understanding the risks involved is that the cost of your debt is usually set and predictable, but the returns on your investments are not. It might be easy to look at the historical returns of the S&P 500 at just under 10 percent a year and assume that it's worth it to put off paying down debt for an S&P 500 ETF or index fund as long as your APR is under 10 percent.

However, that long-term average does not reflect just how chaotic the markets really are. Sure, it might average out to about 10 percent, but some years will be in the negative -- sometimes over 30 percent into the red. Even with bonds -- where your rate of return is fixed -- there is always a chance that the borrower will default and leave you with nothing.

If you have a variable rate loan

Of course, if your loan has variable interest rates, the equation changes yet again. You could see your interest rate rise or fall depending on what the Federal Reserve does, adding another layer of uncertainty to the decision -- especially when it's impossible to say with certainty which direction interest rates are headed in for the long run.

So, although debt will typically have more certainty associated with its costs than investing, that's not always the case and variable rate loans could change things for some borrowers.

Don't forget taxes.

You should also remember that the tax code includes a number of provisions that promote investment, and those can boost the value of investing. In particular, contributions to a 401(k) or traditional IRA are made with before-tax income, meaning that you can invest much more of that money than you would have with your after-tax income that would be used to pay down debt.

That's especially true when you have an employer who matches your 401(k) contributions. If your employer matches, you're essentially getting a chance to not just avoid paying taxes on that income, but you're doubling its value the moment you invest -- before it's even started to accrue returns.

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Some opportunities are unique.

Another important factor to consider is what type of investments you can make. In some very specific cases, you might have access to an investment opportunity that brings with it huge potential returns that could tip the scale. Maybe a specific local real estate investment you're particularly familiar with or a startup company run by a family member where you can get in on the ground floor.

Opportunities like this usually come with enormous risks, but they can also create transformational shifts in wealth when they pay off. Obviously, you have to gauge each opportunity very carefully and make some hard choices, but if you do feel like it's a truly unique chance to get the sort of returns that just don't exist with publicly-traded stocks or bonds, it might be worth putting off paying down debt -- especially if those debts have fixed rates and a reasonable APR.

What really matters with debt and investments

At the end of the day, you certainly shouldn't opt to invest money that could be used to pay down debt unless the expectation for your returns is greater than the interest rate on your debt. If your personal loan has an APR of 15 percent, investing in stocks is probably not going to return enough to make it worthwhile. If that rate is 5 percent, though, you could very well do better with certain investments, especially if that's a fixed rate that doesn't compound.

But, even in circumstances where you might have reasonable expectations for returns higher than your APR, you might still want to take the definite benefits of paying down debt instead of the uncertain benefits associated with investments. When a wrong move might mean having to delay retirement or delay buying a home, opting for the sure thing is hard to argue with.

Which decision is right for you?

Unfortunately, there's no magic bullet for knowing whether your specific circumstances call for you to prioritize paying down debt over everything else. Although paying down debt is typically going to be the smartest use for your money, that doesn't mean you should do so blindly.

Putting off paying down your credit card balance to try your hand at picking some winning stocks is a (really) bad idea, but failing to make regular 401(k) contributions in an effort to pay off your fixed-rate mortgage a couple of years early is probably going to cost you in the long run -- especially if you're missing out on matching funds from your employer by doing so.

So, in a certain sense, Mark Cuban is right: Paying down debt is very rarely going to be a bad idea, and it's almost always the safest choice. But that said, it's still worth taking the time to examine the circumstances of your specific situation to be sure you're not the exception that proves the rule.

Click through to read more about the debts you definitely need to pay off before you retire.

(By Joel Anderson)