Pay Off Debt or Invest? Where Dave Ramsey Is Right and Where the Math Disagrees

👋 Hey, it's Travis

My old student loan had two parts. A federal portion and a provincial portion.

I made the call years ago not to make extra payments. The rate felt low enough that the money would do more work invested. I did some napkin math, felt confident about it, and moved on.

I hadn't revisited it since. So recently I pulled up a spreadsheet and ran the numbers properly and did a bit of research - partly because I wanted to know if I'd actually made the right call and partly because I could hear Dave Ramsey in the back of my head, screaming to pay down debt first.

Turns out, the math can get a bit nuanced. And the research is even more interesting.

This week's Money Monday is how I decided between paying off debt and investing - what people get right, what they get wrong, and the system I use now.

💡 Where Ramsey Is Right

Before I get into where the numbers break, I want to be fair about what he gets right.

Ramsey's system works psychologically. Concentrating payments and closing accounts one by one builds real momentum. One study of about 6,000 clients at a debt settlement firm found that people who closed more accounts were more likely to finish their repayment program, and a start-small approach made them about 14% more likely to be debt-free after a year. The momentum is a real force to consider.

Some people also just need the debt gone before they can focus on anything else. If the monthly obligation is a source of stress that's undermining everything else in their financial life, paying it off first has a value the math doesn't capture. That's a legitimate reason to deviate from the optimal rate comparison.

The problem isn't that Ramsey ignores psychology. It's that his plan applies the same logic to every debt regardless of rate.

📊 Where the Math Breaks

Ramsey's investing logic assumes a 12% annual return. The S&P 500 with dividends reinvested has returned about 9.9% a year since 1926, and about 6.7% after inflation. The 12% figure isn't impossible over a specific stretch - but it's not what the historical record supports as a planning assumption. And returns aren't guaranteed. The S&P 500 was negative in about 24% of individual years since 1926. In about 9% of rolling 10-year periods, annual returns came in at 3% or less.

Paying down debt is a guaranteed return equal to the interest rate. Investing is not.

Here's the math on three debts, each a $20,000 balance with $500 a month to work with over 10 years. I compared paying the debt off fast against making the standard payment and investing the rest, at returns of 4%, 7%, and 9.9%.

Scenario 1: Credit card at 22%

At 22%, that $20k takes 6 years and $16,378 in interest to pay off. Paying it down wins by about $12,800 at 4%, $12,100 at 7%, and $11,100 at 9.9%. Not even close, the math is clear. Pay down credit card debt.

Scenario 2: Student loan at 8.07%

Paying it down wins by about $3,600 at 4% and $1,100 at 7%. At 9.9%, investing wins by about $2,200. The call flips depending on which return you believe.

Scenario 3: Loan at 5.45%

Paying it down wins by about $1,300 at 4%. Investing wins by about $1,600 at 7% and $5,400 at 9.9%. Same flip. The answer depends entirely on the return you assume.

🧠 What the Research Says

Here's where the experts split.

Fidelity draws the line at 6%: above that, pay the debt first; below that, invest (after capturing any employer match). Others argue the line should be lower because paying debt is risk-free and investing isn't - a guaranteed 5.45% return can be worth more than a probable-but-not-certain 6.7%. And some say that when it's close, peace of mind is a legitimate tiebreaker.

The behavioral research gets even more interesting.

A 2024 American Economic Review study found that about a third of participants in online experiments prioritized paying down debt even when better options were available. People were also about 50% less likely to borrow money than to withdraw savings for the same financial gain. We treat debt as so psychologically costly that we avoid it even when borrowing would be the smarter move.

But at the same time: over 80% of households carrying credit card debt also held low-yield savings they could have used to pay it down and didn't. Put those together and the pattern is that we make debt decisions by feel, not by rate. Some of us rush to clear cheap debt, and some of us sit on savings while a 20% card keeps growing. Neither direction is fully rational.

Being done with a debt has real value. It reduces cognitive load, removes a monthly obligation, and some people sleep better. The question is whether you know what you're paying for that peace of mind - and whether the price is worth it at your specific rate.

📋 My Rule

Here's the 4-step process I follow and recommend.

1. Capture your full employer match first. Always. A match is effectively a 100% return on that dollar. Nothing beats it.
2. Above roughly 7%: pay the debt first. The return is guaranteed, and at this rate it's hard for a risky investment to justify the gamble. A historically average market can still come out ahead of a rate like 8%, but it isn't guaranteed to, and paying the debt is. Fidelity's line sits near 6%, so treat 7% as a reasonable edge, not a law.
3. Between roughly 4% and 7%: real judgment call. Fidelity says invest. Others say pay down because the guarantee matters. I say if peace of mind matters more than the math, or if you have a low risk tolerance, pay anything above 4% first.
4. Below roughly 4%: invest. The historical probability of investment returns beating a sub-4% debt rate over a decade is high enough that paying it first is likely leaving money on the table.

One thing worth adding before you compare debt rates to stocks: compare the debt rate to what safe money earns first. If a high-yield savings account is paying 4.5% and your debt is at 4%, that's a different picture than comparing 4% to a 9.9% stock return.

Not all debt is bad. But all debt has a price. Compare that price to what your money could do elsewhere - and be honest about what peace of mind is worth to you.

Once you can see every rate in one place, the decision gets a lot less emotional.

✅ Money Moves to Make This Week

🎯 Action 1: Write down every debt you have and the interest rate on each (10 minutes)

Check your statement or log into the servicer's site. This list is the starting point for everything else.

🎯 Action 2: Sort each rate into one of the three rungs and circle anything in the 4-7% zone (5 minutes)

Above 7%: pay it first. Below 4%: invest. Between 4-7%: you have a real decision to make and temperament matters. Circling the contested ones is the first step to making that call consciously instead of by default.

🎯 Action 3: Check whether you're capturing your full employer match (5 minutes)

If you have a workplace retirement plan and you're not getting the full match, that's the first dollar to fix - before any debt payoff math matters. Find out what the contribution form is and what the match threshold is. This one is a guaranteed return nothing else can beat.

💬 Fund(amental) Quote of the Week

Most people are either paying debt aggressively or leaving it alone - and in both cases they made the call without running the actual numbers. The math doesn't have to be complicated. You just have to do it once.

Until next Monday,

Travis